Use __HAVE_DISTINCT_FLOAT128 in tgmath.h.

When _Float128 is ABI-equivalent to long double, there is no need for
tgmath.h to have any special _Float128 handling: it's always OK to
call the long double versions of functions for _Float128 arguments in
that case, and the logic to determine return types is generic.  Thus,
this patch changes the use of __HAVE_FLOAT128 to
__HAVE_DISTINCT_FLOAT128, as a minor optimization to reduce the size
of the macro expansions in the ABI-equivalent case.

Tested for x86_64.

	* math/tgmath.h [__HAVE_FLOAT128]: Change conditional to
	[__HAVE_DISTINCT_FLOAT128].

1 files changed, 3 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 101a94351f..f2c420423d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2017-08-25  Joseph Myers  <joseph@codesourcery.com>
 
+	* math/tgmath.h [__HAVE_FLOAT128]: Change conditional to
+	[__HAVE_DISTINCT_FLOAT128].
+
 	* math/math.h (_MSUFTO_): Define and undefine for each inclusion
 	of <bits/math-finite.h>.
 	(__MATH_DECLARING_LDOUBLE): Do not define and undefine for each