Fixup for r293885: Update external.cc testcase to include the forgotten stdlib.h.

llvm-svn: 295002

compiler-rt/test/tsan/Darwin/external.cc

@@ -17,6 +17,7 @@
 #include <dlfcn.h>
 #include <pthread.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 struct MyObject;
 typedef MyObject *MyObjectRef;