Bug 1345978, part 1 - Add a way to get the platform build id without the service manager. r=froydnj

The next patch needs this value early in startup, before the service
manager is available.

MozReview-Commit-ID: LAfnzV2nfiR

--HG--
extra : rebase_source : 7230335461d06157d916b02fbe37f623fd233fae

toolkit/xre/nsAppRunner.cpp

@@ -5015,6 +5015,14 @@ mozilla::BrowserTabsRemoteAutostart()
   return gBrowserTabsRemoteAutostart;
 }
 
+namespace mozilla {
+const char*
+PlatformBuildID()
+{
+  return gToolkitBuildID;
+}
+}
+
 void
 SetupErrorHandling(const char* progname)
 {

toolkit/xre/nsAppRunner.h

@@ -118,6 +118,9 @@ namespace mozilla {
 namespace startup {
 extern GeckoProcessType sChildProcessType;
 } // namespace startup
+
+const char* PlatformBuildID();
+
 } // namespace mozilla
 
 /**