Add means for running some tests only o-o-p, add messaging o-o-p test.

ppapi/c/pp_macros.h

Index: ppapi/c/pp_macros.h
diff --git a/ppapi/c/pp_macros.h b/ppapi/c/pp_macros.h
index e5cd7dd0d5da0ff6f73cd8858ef5271f12ba9ce9..055c8a93834746a450135527569d1cb78688fea8 100644
--- a/ppapi/c/pp_macros.h
+++ b/ppapi/c/pp_macros.h
@@ -93,6 +93,13 @@ PP_COMPILE_ASSERT_SIZE_IN_BYTES_IMPL(NAME, struct NAME, SIZE)
 #define PP_COMPILE_ASSERT_ENUM_SIZE_IN_BYTES(NAME, SIZE) \
 PP_COMPILE_ASSERT_SIZE_IN_BYTES_IMPL(NAME, enum NAME, SIZE)
 
+#if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
+    defined(__OpenBSD__) || defined(__sun) || defined(__native_client__)
+#define PPAPI_HAS_POSIX_THREADS 1
+#elif defined (_MSC_VER)
+#define PPAPI_HAS_WINDOWS_THREADS 1
+#endif
+
 /**
  * @}
  * End of addtogroup PP