Remove unused macros from libm-test.inc.

This patch removes various no-longer-used macros from libm-test.inc.
NO_TEST_INLINE_FLOAT, NO_TEST_INLINE_DOUBLE and M_PI_6l would have
been used before relevant tests were moved to auto-libm-test-in.
TEST_COND_x86_64 and TEST_COND_x86 were for tests in auto-libm-test-in
XFAILed for x86, and are no longer relevant now the bugs in question
have been fixed and the XFAILing removed (if future x86-specific
XFAILs become needed, they can always be added back).

Tested for x86_64 and x86.

	* math/libm-test.inc (NO_TEST_INLINE_FLOAT): Remove macro.
	(NO_TEST_INLINE_DOUBLE): Likewise.
	(TEST_COND_x86_64): Likewise.
	(TEST_COND_x86): Likewise.
	(M_PI_6l): Likewise.