[modules] Fix iterator invalidation issue with names being added to a module
while we're writing out the identifier table.

llvm-svn: 231890
diff --git a/clang/test/Modules/Inputs/invalidate-identifiers/b.h b/clang/test/Modules/Inputs/invalidate-identifiers/b.h
new file mode 100644
index 0000000..2af246d
--- /dev/null
+++ b/clang/test/Modules/Inputs/invalidate-identifiers/b.h
@@ -0,0 +1,2 @@
+extern int v;
+#include "a.h"