Fixed warning : 'va_copy' : macro redefinition
MSVC 2013 has got va_copy
Compare
http://msdn.microsoft.com/en-us/library/kb57fad8(v=vs.110).aspx
and
http://msdn.microsoft.com/en-us/library/kb57fad8.aspx.

Change-Id: If0937c76e8d250cde4b343844f3d35c980bf0921
diff --git a/internal/ceres/stringprintf.cc b/internal/ceres/stringprintf.cc
index eabdcb6..0f85f05 100644
--- a/internal/ceres/stringprintf.cc
+++ b/internal/ceres/stringprintf.cc
@@ -43,7 +43,9 @@
 
 #ifdef _MSC_VER
 enum { IS_COMPILER_MSVC = 1 };
+#if _MSC_VER < 1800
 #define va_copy(d, s) ((d) = (s))
+#endif
 #else
 enum { IS_COMPILER_MSVC = 0 };
 #endif