Fix m68k bits/fenv.h for no-FPU ColdFire.

Fix m68k bits/fenv.h for no-FPU ColdFire.

The m68k bits/fenv.h is in sysdeps/m68k/fpu/, meaning that no-FPU
ColdFire instead gets the generic (top-level) bits/fenv.h.

That top-level bits/fenv.h defines no rounding mode constants.  That
no longer works for building glibc tests: some tests fail to build (at
least with warnings) if no rounding mode macros are defined, so at
least FE_TONEAREST must be defined in all cases (as various
architectures without rounding mode support indeed do), while
__FE_UNDEFINED must be defined in the case where not all the standard
rounding modes are supported.

On general principles of supporting multilib toolchains with a single
set of headers shared between multilibs for a given architecture, it's
also desirable for the same bits/fenv.h header to work for both FPU
and no-FPU configurations.  Thus, this patch moves the m68k
bits/fenv.h to sysdeps/m68k/bits/fenv.h, and inserts appropriate
conditionals to handle the no-FPU case.  All the exception macros, and
FE_NOMASK_ENV, are disabled in the no-FPU case; FE_ALL_EXCEPT is
defined to 0 in that case.  All rounding modes except FE_TONEAREST are
disabled in that case, and __FE_UNDEFINED is defined accordingly.  To
avoid an unnecessary ABI change, fenv_t is defined in the no-FPU case
to match the definition it would have got from the generic
bits/fenv.h.

This suffices to get a clean glibc and testsuite build for this
configuration with build-many-glibcs.py (and keeps a clean build for
the other m68k configurations); it has not been otherwise tested.

	* sysdeps/m68k/fpu/bits/fenv.h: Move to ....
	* sysdeps/m68k/bits/fenv.h: ... here.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_INEXACT): Do
	not define.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_DIVBYZERO):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_UNDERFLOW):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_OVERFLOW):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_INVALID):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_ALL_EXCEPT):
	Define to 0.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__]
	(__FE_UNDEFINED): New enum constant.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_TOWARDZERO):
	Do not define.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_DOWNWARD):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_UPWARD):
	Likewise.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (fenv_t): Define
	to match generic bits/fenv.h.
	[!__HAVE_68881__ && !__HAVE_FPU__ && !__mcffpu__] (FE_NOMASK_ENV):
	Do not define.