Fix libm fesetround namespace (bug 17748).

Fix libm fesetround namespace (bug 17748).

Continuing the fixes for C90 libm functions calling C99 fe* functions,
this patch fixes the case of fesetround by making it a weak alias of
__fesetround and making the affected code call __fesetround.  An
existing __fesetround function in fenv_libc.h for powerpc is renamed
to __fesetround_inline.

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

	[BZ #17748]
	* include/fenv.h (__fesetround): Declare.  Use libm_hidden_proto.
	* math/fesetround.c (fesetround): Rename to __fesetround and
	define as weak alias of __fesetround.  Use libm_hidden_weak.
	* sysdeps/aarch64/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/alpha/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/arm/fesetround.c (fesetround): Likewise.
	* sysdeps/hppa/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/i386/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/ia64/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/m68k/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/mips/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/powerpc/fpu/fenv_libc.h (__fesetround): Rename to
	__fesetround_inline.
	* sysdeps/powerpc/fpu/fenv_private.h (libc_fesetround_ppc): Call
	__fesetround_inline instead of __fesetround.
	* sysdeps/powerpc/fpu/fesetround.c (fesetround): Rename to
	__fesetround and define as weak alias of __fesetround.  Use
	libm_hidden_weak.  Call __fesetround_inline instead of
	__fesetround.
	* sysdeps/powerpc/nofpu/fesetround.c (fesetround): Rename to
	__fesetround and define as weak alias of __fesetround.  Use
	libm_hidden_weak.
	* sysdeps/powerpc/powerpc32/e500/nofpu/fesetround.c (fesetround):
	Likewise.
	* sysdeps/s390/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/sh/sh4/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/sparc/fpu/fesetround.c (fesetround): Likewise.
	* sysdeps/tile/math_private.h (__fesetround): New inline function.
	* sysdeps/x86_64/fpu/fesetround.c (fesetround): Rename to
	__fesetround and define as weak alias of __fesetround.  Use
	libm_hidden_weak.
	* sysdeps/generic/math_private.h (default_libc_fesetround): Call
	__fesetround instead of fesetround.
	(default_libc_feholdexcept_setround): Likewise.
	(libc_feholdsetround_ctx): Likewise.
	(libc_feholdsetround_noex_ctx): Likewise.