Fix windows build.

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index d6c6b2f21f5552feef9c5a11e84b5d6d4f1126d2..9ec2174fcafcb042f645a9513299c62d9d9c37b0 100755
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -21,6 +21,12 @@
 #define DART_EXTERN_C
 #endif
 
+// __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
+// enable platform independent printf format specifiers.
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS
+#endif
+
 #if defined(__CYGWIN__)
 #error Tool chain and platform not supported.
 #elif defined(_WIN32)
@@ -38,11 +44,6 @@ typedef unsigned __int64 uint64_t;
 #define DART_EXPORT DART_EXTERN_C
 #endif
 #else
-// __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
-// enable platform independent printf format specifiers.
-#ifndef __STDC_FORMAT_MACROS
-#define __STDC_FORMAT_MACROS
-#endif
 #include <inttypes.h>
 #include <stdbool.h>
 #if __GNUC__ >= 4