make windows code built with clangcl include the _posix source code. …

make windows code built with clangcl include the _posix source code.  depot_tools excludes these source files now, so they need to be manually included.
BUG=435
TESTED=clangcl local build on windows
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/46199004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1394 16f28f9a-4ce2-e073-06de-1de4eb20be90

source/scale_win.cc

@@ -17,8 +17,12 @@ extern "C" {
 #endif
 
 // This module is for Visual C x86.
-#if !defined(LIBYUV_DISABLE_X86) && defined(_M_IX86) && \
-    defined(_MSC_VER) && !defined(__clang__)
+#if !defined(LIBYUV_DISABLE_X86) && defined(_M_IX86) && defined(_MSC_VER)
+
+// ClangCL use posix source instead.
+#if defined(__clang__)
+#include "source/scale_posix.cc"
+#else
 
 // Offsets for source bytes 0 to 9
 static uvec8 kShuf0 =
@@ -1390,6 +1394,7 @@ int FixedDiv1_X86(int num, int div) {
   }
 }
 
+#endif  // defined(__clang__)
 #endif  // !defined(LIBYUV_DISABLE_X86) && defined(_M_IX86) && ...
 
 #ifdef __cplusplus