cmath: Extend/update comment.

2011-08-18  Marc Glisse  <marc.glisse@normalesup.org>

	* include/tr1/cmath: Extend/update comment.

From-SVN: r177873

libstdc++-v3/ChangeLog

+2011-08-18  Marc Glisse  <marc.glisse@normalesup.org>
+
+	* include/tr1/cmath: Extend/update comment.
+
 2011-08-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR libstdc++/50119

libstdc++-v3/include/tr1/cmath

@@ -567,6 +567,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Note: we deal with fabs in a special way, because an using std::fabs
   // would bring in also the overloads for complex types, which in C++0x
   // mode have a different return type.
+  // With __CORRECT_ISO_CPP_MATH_H_PROTO1, math.h imports std::fabs in the
+  // global namespace after the declarations of the float / double / long
+  // double overloads but before the std::complex overloads.
   using ::fabs;
 
 #ifndef __CORRECT_ISO_CPP_MATH_H_PROTO1