cmath: Revert fix for libstdc++/58625...

2015-08-19  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/c_global/cmath: Revert fix for libstdc++/58625, no
	longer necessary (__builtin_signbit is now type-generic).

From-SVN: r227006

libstdc++-v3/ChangeLog

+2015-08-19  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* include/c_global/cmath: Revert fix for libstdc++/58625, no
+	longer necessary (__builtin_signbit is now type-generic).
+
 2015-08-18  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR c++/67216

libstdc++-v3/include/c_global/cmath

@@ -650,10 +650,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     isnormal(_Tp __x)
     { return __x != 0 ? true : false; }
 
-  // The front-end doesn't provide a type generic builtin (libstdc++/58625).
+  // Note: c++/36757 is fixed, __builtin_signbit is type-generic.
   constexpr bool
   signbit(float __x)
-  { return __builtin_signbitf(__x); }
+  { return __builtin_signbit(__x); }
 
   constexpr bool
   signbit(double __x)
@@ -661,7 +661,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   constexpr bool
   signbit(long double __x)
-  { return __builtin_signbitl(__x); }
+  { return __builtin_signbit(__x); }
 
   template<typename _Tp>
     constexpr typename __gnu_cxx::__enable_if<__is_integer<_Tp>::__value,