Expand #include_next in float.h from mingw to _msc_ver.

A test for this is checking if this compiles:

    #include <float.h>

    inline bool IsFinite(const double& number) {
     return _finite(number) != 0;
    }

That depends however on either mingw or msvc being installed, and
chapuni tells me there might be issues with float.h on mingw, so
no automated test is added.

llvm-svn: 155507
diff --git a/clang/lib/Headers/float.h b/clang/lib/Headers/float.h
index 65b517d..2cb13d3 100644
--- a/clang/lib/Headers/float.h
+++ b/clang/lib/Headers/float.h
@@ -28,7 +28,7 @@
  * additional definitions provided for Windows.
  * For more details see http://msdn.microsoft.com/en-us/library/y0ybw9fy.aspx
  */
-#if defined(__MINGW32__) && \
+#if (defined(__MINGW32__) || defined(_MSC_VER)) && \
     defined(__has_include_next) && __has_include_next(<float.h>)
 #  include_next <float.h>