Fix bits/math-finite.h _MSUF_ expansion namespace (bug 22028).

Fix bits/math-finite.h _MSUF_ expansion namespace (bug 22028).

The current bits/math-finite.h approach to defining functions for
different types, involving math.h defining _MSUF_ and _MSUFTO_ for the
function suffixes involved, is not namespace-clean if one of those
suffixes (f, l, f128) is defined as a macro by the user before math.h
is included; too many levels of macro expansion occur.  Instead, those
suffixes should appear directly in the expansion of the macro using ##
so they don't get expanded even if defined as macros by the user (that
is, math.h should be defining __REDIRFROM_X and __REDIRTO_X directly
to use those suffixes rather than suffixes being passed as an argument
by macro callers).  This patch makes that change.

Tested for x86_64.

	[BZ #22028]
	* math/math.h [__FINITE_MATH_ONLY__ && __FINITE_MATH_ONLY__ > 0]
	(_MSUF_): Remove macro.
	[__FINITE_MATH_ONLY__ && __FINITE_MATH_ONLY__ > 0] (_MSUFTO_):
	Likewise.
	[__FINITE_MATH_ONLY__ && __FINITE_MATH_ONLY__ > 0]
	(__REDIRFROM_X): New macro.
	[__FINITE_MATH_ONLY__ && __FINITE_MATH_ONLY__ > 0] (__REDIRTO_X):
	Likewise.
	* math/bits/math-finite.h (__REDIRFROM_X): Remove macro.
	(__REDIRTO_X): Likewise.
	(__MATH_REDIRCALL): Do not pass _MSUF_ or _MSUFTO_ macro
	arguments.
	(__MATH_REDIRCALL_2): Likewise.
	(__MATH_REDIRCALL_INTERNAL): Likewise.
	(__REDIRFROM (lgamma, , _MSUF_)): Likewise.
	(__REDIRFROM (gamma, , _MSUF_)): Likweise.
	(__REDIRFROM (__gamma, _r_finite, _MSUF_)): Likewise.
	(__REDIRFROM (tgamma, , _MSUF_)): Likewise.
	* math/test-finite-macros.c: New file.
	* math/Makefile (tests): Add test-finite-macros.
	(CFLAGS-test-finite-macros.c): New variable.