Fix libm fesetenv namespace (bug 17748).

Fix libm fesetenv namespace (bug 17748).

Continuing the fixes for C90 libm functions calling C99 fe* functions,
this patch fixes the case of fesetenv by making it a weak alias of
__fesetenv and making the affected code (including various copies of
feupdateenv which also gets called from C90 functions) call
__fesetenv.

Tested for x86_64 (testsuite, and that disassembly of installed shared
libraries is unchanged by the patch).  Also tested for ARM
(soft-float) that fesetenv failures disappear from the linknamespace
test results (fsetround and feupdateenv remain to be addressed to
complete fixing bug 17748).

	[BZ #17748]
	* include/fenv.h (__fesetenv): Use libm_hidden_proto.
	* math/fesetenv.c (__fesetenv): Use libm_hidden_def.
	* sysdeps/aarch64/fpu/fesetenv.c (fesetenv): Rename to __fesetenv
	and define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/alpha/fpu/fesetenv.c (__fesetenv): Use libm_hidden_def.
	* sysdeps/arm/fesetenv.c (fesetenv): Rename to __fesetenv and
	define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/hppa/fpu/fesetenv.c (fesetenv): Likewise.
	* sysdeps/i386/fpu/fesetenv.c (__fesetenv): Use libm_hidden_def.
	* sysdeps/ia64/fpu/fesetenv.c (fesetenv): Rename to __fesetenv and
	define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/m68k/fpu/fesetenv.c (__fesetenv): Use libm_hidden_def.
	* sysdeps/mips/fpu/fesetenv.c (fesetenv): Rename to __fesetenv and
	define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/powerpc/fpu/fesetenv.c (__fesetenv): Use
	libm_hidden_def.
	* sysdeps/powerpc/nofpu/fesetenv.c (__fesetenv): Likewise.
	* sysdeps/powerpc/powerpc32/e500/nofpu/fesetenv.c (__fesetenv):
	Likewise.
	* sysdeps/s390/fpu/fesetenv.c (fesetenv): Rename to __fesetenv and
	define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/sh/sh4/fpu/fesetenv.c (fesetenv): Likewise.
	* sysdeps/sparc/fpu/fesetenv.c (__fesetenv): Use libm_hidden_def.
	* sysdeps/tile/math_private.h (__fesetenv): New inline function.
	* sysdeps/x86_64/fpu/fesetenv.c (fesetenv): Rename to __fesetenv
	and define as weak alias of __fesetenv.  Use libm_hidden_weak.
	* sysdeps/generic/math_private.h (default_libc_fesetenv): Use
	__fesetenv instead of fesetenv.
	(libc_feresetround_noex_ctx): Likewise.
	* sysdeps/alpha/fpu/feupdateenv.c (__feupdateenv): Likewise.
	* sysdeps/hppa/fpu/feupdateenv.c (feupdateenv): Likewise.
	* sysdeps/i386/fpu/feupdateenv.c (__feupdateenv): Likewise.
	* sysdeps/ia64/fpu/feupdateenv.c (feupdateenv): Likewise.
	* sysdeps/m68k/fpu/feupdateenv.c (__feupdateenv): Likewise.
	* sysdeps/mips/fpu/feupdateenv.c (feupdateenv): Likewise.
	* sysdeps/powerpc/nofpu/feupdateenv.c (__feupdateenv): Likewise.
	* sysdeps/powerpc/powerpc32/e500/nofpu/feupdateenv.c
	(__feupdateenv): Likewise.
	* sysdeps/s390/fpu/feupdateenv.c (feupdateenv): Likewise.
	* sysdeps/sh/sh4/fpu/feupdateenv.c (feupdateenv): Likewise.
	* sysdeps/sparc/fpu/feupdateenv.c (__feupdateenv): Likewise.
	* sysdeps/x86_64/fpu/feupdateenv.c (__feupdateenv): Likewise.