disable loplugin memoryvar for now

seems to be crashing with latest(trunk) clang sometimes

Change-Id: Ice92b35deb6cb4610dbd53f570d0b43e9d2a2834

compilerplugins/clang/memoryvar.cxx

@@ -232,7 +232,7 @@ bool MemoryVar::VisitReturnStmt(const ReturnStmt *returnStmt)
     return true;
 }
 
-loplugin::Plugin::Registration< MemoryVar > X("memoryvar");
+loplugin::Plugin::Registration< MemoryVar > X("memoryvar", false);
 
 }