Make drem an alias of remainder (bug 16171).

Make drem an alias of remainder (bug 16171).

The libm drem functions just call the corresponding __remainder
functions.  This patch removes the unnecessary wrappers by making them
into weak aliases at the ELF level.

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #16171]
	* math/w_remainder.c (drem): Define as weak alias of __remainder.
	[NO_LONG_DOUBLE] (dreml): Define as weak alias of __remainder.
	* math/w_remainderf.c (dremf): Define as weak alias of
	__remainderf.
	* math/w_remainderl.c (dreml): Define as weak alias of
	__remainderl.
	* sysdeps/ia64/fpu/e_remainder.S (drem): Define as weak alias of
	__remainder.
	* sysdeps/ia64/fpu/e_remainderf.S (dremf): Define as weak alias of
	__remainderf.
	* sysdeps/ia64/fpu/e_remainderl.S (dreml): Define as weak alias of
	__remainderl.
	* sysdeps/ieee754/ldbl-opt/nldbl-remainder.c (dreml): Define as
	weak alias of remainderl.
	* sysdeps/ieee754/ldbl-opt/w_remainder.c
	[LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)] (__drem): Define as strong
	alias of __remainder.
	[LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)] (dreml): Use compat_symbol.
	* sysdeps/ieee754/ldbl-opt/w_remainderl.c (__dreml): Define as
	strong alias of __remainderl.
	(dreml): Use long_double_symbol.
	* math/Makefile (libm-calls): Remove w_drem.
	* sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Remove drem.
	(CFLAGS-nldbl-drem.c): Remove variable.
	(CFLAGS-nldbl-remainder.c): Add -fno-builtin-dreml.
	* math/w_drem.c: Remove file.
	* math/w_dremf.c: Likewise.
	* math/w_dreml.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/nldbl-drem.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/w_drem.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/w_dreml.c: Likewise.