Sync 'in class initialization of static const double' extension up with GCC,
and split it out of -Wgnu into its own warning flag.

 * In C++11, this is now a hard error (GCC has no extension here in C++11 mode).
   The error can be disabled with -Wno-static-float-init, and has a fixit to
   add 'constexpr'.

 * In C++98, this is still an ExtWarn, but is now controlled by
   -Wstatic-float-init as well as -Wgnu.

llvm-svn: 173414
diff --git a/clang/test/CXX/class/class.static/class.static.data/p3.cpp b/clang/test/CXX/class/class.static/class.static.data/p3.cpp
index 117997e..0d104e0 100644
--- a/clang/test/CXX/class/class.static/class.static.data/p3.cpp
+++ b/clang/test/CXX/class/class.static/class.static.data/p3.cpp
@@ -13,7 +13,7 @@
   static const int d2 = 0;
 
   static constexpr double e = 0.0; // ok
-  static const double f = 0.0; // expected-warning {{extension}} expected-note {{use 'constexpr' specifier}}
+  static const double f = 0.0; // expected-error {{requires 'constexpr' specifier}}
   static char *const g = 0; // expected-error {{requires 'constexpr' specifier}}
   static const NonLit h = NonLit(); // expected-error {{must be initialized out of line}}
 };