[msan] Add a check for recursive __msan_init.

llvm-svn: 197218

compiler-rt/lib/msan/msan.cc

@@ -275,6 +275,7 @@ void __msan_warning_noreturn() {
 }
 
 void __msan_init() {
+  CHECK(!msan_init_is_running);
   if (msan_inited) return;
   msan_init_is_running = 1;
   SanitizerToolName = "MemorySanitizer";