ensure that heap checker initialization actually calls malloc

I.e. all recent compilers (both gcc and clang) optimize out delete(new
int) sequence to nothing. We call to tc_new and tc_delete directly to
suppress this optimization.

src/heap-checker-bcad.cc

@@ -66,7 +66,12 @@ class HeapLeakCheckerGlobalPrePost {
       // MallocHook_InitAtFirstAllocation_HeapLeakChecker.  See malloc_hook.cc.
       // This is done in this roundabout fashion in order to avoid self-deadlock
       // if we directly called HeapLeakChecker_BeforeConstructors here.
-      delete new int;
+      //
+      // We use explicit global operator new/delete functions since
+      // plain 'naked' delete new int modern compilers optimize out to
+      // nothing. And apparently calling those global new/delete
+      // functions is assumed by compilers to be 'for effect' as well.
+      (operator delete)((operator new)(4));
       // This needs to be called before the first allocation of an STL
       // object, but after libc is done setting up threads (because it
       // calls setenv, which requires a thread-aware errno).  By