Add run-time CHECK to smoke-test allocator overrides

third_party/tcmalloc/chromium/src/tcmalloc.cc

Index: third_party/tcmalloc/chromium/src/tcmalloc.cc
diff --git a/third_party/tcmalloc/chromium/src/tcmalloc.cc b/third_party/tcmalloc/chromium/src/tcmalloc.cc
index 4709411718bc9eba3e96af3d4b4cc6ac1233284b..3077b75972645cf82958edacb65180bbea1db384 100644
--- a/third_party/tcmalloc/chromium/src/tcmalloc.cc
+++ b/third_party/tcmalloc/chromium/src/tcmalloc.cc
@@ -1390,7 +1390,13 @@ inline void do_malloc_stats() {
 }
 
 inline int do_mallopt(int cmd, int value) {
-  return 1;     // Indicates error
+  if (cmd == TC_MALLOPT_IS_OVERRIDDEN_BY_TCMALLOC)
+    return TC_MALLOPT_IS_OVERRIDDEN_BY_TCMALLOC;
+
+  // 1 is the success return value according to man mallopt(). However (see the
+  // BUGS section in the manpage), most implementations return always 1.
+  // This code is just complying with that (buggy) expectation.
+  return 1;
 }
 
 #ifdef HAVE_STRUCT_MALLINFO