Fix libm mpone, mptwo namespace (bug 17616).

Fix libm mpone, mptwo namespace (bug 17616).

libm uses symbols mpone and mptwo for internal purposes.  This patch
moves them to the implementation namespace (__mpone and __mptwo).

Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by the patch).

	[BZ #17616]
	* sysdeps/ieee754/dbl-64/mpa.c (mpone): Rename to __mpone.
	(mptwo): Rename to __mptwo.
	(__inv): Use __mptwo instead of mptwo.
	* sysdeps/ieee754/dbl-64/mpa.h (mpone): Rename to __mpone.
	(mptwo): Rename to __mptwo.
	* sysdeps/ieee754/dbl-64/mpatan.c (__mpatan): Use __mpone instead
	of mpone and __mptwo instead of mptwo.
	* sysdeps/ieee754/dbl-64/mpatan2.c (__mpatan2): Use __mpone
	instead of mpone.
	* sysdeps/ieee754/dbl-64/mpexp.c (__mpexp): Likewise.
	* sysdeps/ieee754/dbl-64/mplog.c (__mplog): Likewise.
	* sysdeps/ieee754/dbl-64/sincos32.c (__c32): Use __mpone instead
	of mpone and __mptwo instead of mptwo.
	(__mpranred): Use __mpone instead of mpone.
	* conform/Makefile (test-xfail-ISO/math.h/linknamespace): Remove
	variable.
	(test-xfail-ISO99/complex.h/linknamespace): Likewise.
	(test-xfail-ISO99/math.h/linknamespace): Likewise.
	(test-xfail-ISO99/tgmath.h/linknamespace): Likewise.
	(test-xfail-ISO11/complex.h/linknamespace): Likewise.
	(test-xfail-ISO11/math.h/linknamespace): Likewise.
	(test-xfail-ISO11/tgmath.h/linknamespace): Likewise.
	(test-xfail-XPG3/math.h/linknamespace): Likewise.
	(test-xfail-XPG4/math.h/linknamespace): Likewise.
	(test-xfail-POSIX/math.h/linknamespace): Likewise.
	(test-xfail-UNIX98/math.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K/complex.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K/math.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K/tgmath.h/linknamespace): Likewise.
	(test-xfail-POSIX2008/complex.h/linknamespace): Likewise.
	(test-xfail-POSIX2008/math.h/linknamespace): Likewise.
	(test-xfail-POSIX2008/tgmath.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K8/complex.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K8/math.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K8/tgmath.h/linknamespace): Likewise.