Fix sys/ucontext.h namespace from signal.h etc. inclusion (bug 21457).

Fix sys/ucontext.h namespace from signal.h etc. inclusion (bug 21457).

The various sys/ucontext.h headers include <signal.h> and all the
headers split out of <bits/sigstack.h>.  (Except that the powerpc
version does not include <signal.h>.)

None of the standard versions defining ucontext.h require or permit
such inclusions; rather, they all say that the stack_t and sigset_t
types from signal.h are defined.  This patch fixes the headers to
include just the bits/ headers for those types (and the existing
includes of bits/sigcontext.h).  Since bits/types/sigset_t.h is now
being included instead of bits/types/__sigset_t.h, __sigset_t uses in
the headers are replaced by direct use of the public sigset_t type.
sysdeps/unix/sysv/linux/x86/bits/sigcontext.h was relying on the prior
inclusion of <signal.h> to define types such as __uint32_t, so gets a
bits/types.h include added to provide those types.

Although one could keep some or all of the includes under a __USE_MISC
conditional, that seems unnecessary to me, especially given the lack
of a <signal.h> include in the powerpc version meaning that portable
programs already cannot rely on such an include.

Tested for x86_64 and x86, and with build-many-glibcs.py.  As with
other such fixes, more namespace issues remain so this does not permit
any XFAILs to be removed or bugs to be closed.

	[BZ #21457]
	* sysdeps/arm/sys/ucontext.h: Do not include <signal.h>,
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/generic/sys/ucontext.h: Do not include <signal.h>,
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/i386/sys/ucontext.h: Do not include <signal.h>,
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/m68k/sys/ucontext.h: Do not include <signal.h>,
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/mips/sys/ucontext.h: Do not include <signal.h>,
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/alpha/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/arm/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/hppa/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/ia64/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h>.
	* sysdeps/unix/sysv/linux/m68k/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/mips/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/nios2/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h: Do not include
	<bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.
	* sysdeps/unix/sysv/linux/s390/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/tile/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.
	* sysdeps/unix/sysv/linux/x86/bits/sigcontext.h: Include
	<bits/types.h>.
	* sysdeps/unix/sysv/linux/x86/sys/ucontext.h: Do not include
	<signal.h>, <bits/sigstack.h>, <bits/types/struct_sigstack.h> or
	<bits/ss_flags.h>.  Include <bits/types/sigset_t.h> instead of
	<bits/types/__sigset_t.h>.
	(ucontext_t): Use sigset_t instead of __sigset_t.