Mojo: Move message pipe types/constants/functions from mojo/public/c/system/core.h to .../message_p…

mojo/public/c/system/functions.h

Index: mojo/public/c/system/functions.h
diff --git a/mojo/public/c/system/functions.h b/mojo/public/c/system/functions.h
index fa2bd068cc1bdbe01dd6c3d8afc1daf49a99957c..a0330fec3f559c41c3b9825a66b53977d81a34cf 100644
--- a/mojo/public/c/system/functions.h
+++ b/mojo/public/c/system/functions.h
@@ -14,6 +14,10 @@
 #include "mojo/public/c/system/system_export.h"
 #include "mojo/public/c/system/types.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 // Note: Pointer parameters that are labelled "optional" may be null (at least
 // under some circumstances). Non-const pointer parameters are also labeled
 // "in", "out", or "in/out", to indicate how they are used. (Note that how/if
@@ -21,10 +25,6 @@
 // operation's success/failure. E.g., a separate |flags| parameter may control
 // whether a given "in/out" parameter is used for input, output, or both.)
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 // Platform-dependent monotonically increasing tick count representing "right
 // now." The resolution of this clock is ~1-15ms.  Resolution varies depending
 // on hardware/operating system configuration.