Bug 867914: Declare SharedStub as returning nsresult in xptcstubs_sparc64_openbsd.cpp. r=landry

Fixes a build issue on NetBSD/sparc64, no apparent fallout on OpenBSD/sparc64

xpcom/reflect/xptcall/src/md/unix/xptcstubs_sparc64_openbsd.cpp

@@ -83,7 +83,7 @@ PrepareAndDispatch(nsXPTCStubBase* self, uint64_t methodIndex, uint64_t* args)
     return result;
 }
 
-extern "C" int SharedStub(int, int*);
+extern "C" nsresult SharedStub(int, int*);
 
 #define STUB_ENTRY(n) \
 nsresult nsXPTCStubBase::Stub##n() \