Revert 126715 - Update the tcmalloc vendor branch to r144 (gperftools 2.0).

third_party/tcmalloc/vendor/src/libc_override_osx.h

Index: third_party/tcmalloc/vendor/src/libc_override_osx.h
===================================================================
--- third_party/tcmalloc/vendor/src/libc_override_osx.h	(revision 126727)
+++ third_party/tcmalloc/vendor/src/libc_override_osx.h	(working copy)
@@ -75,7 +75,7 @@
 #ifdef HAVE_FEATURES_H
 #include <features.h>
 #endif
-#include <gperftools/tcmalloc.h>
+#include <google/tcmalloc.h>
 
 #if !defined(__APPLE__)
 # error libc_override_glibc-osx.h is for OS X distributions only.
@@ -84,19 +84,6 @@
 #include <AvailabilityMacros.h>
 #include <malloc/malloc.h>
 
-// from AvailabilityMacros.h
-#if defined(MAC_OS_X_VERSION_10_6) && \
-    MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
-extern "C" {
-  // This function is only available on 10.6 (and later) but the
-  // LibSystem headers do not use AvailabilityMacros.h to handle weak
-  // importing automatically.  This prototype is a copy of the one in
-  // <malloc/malloc.h> with the WEAK_IMPORT_ATTRBIUTE added.
-  extern malloc_zone_t *malloc_default_purgeable_zone(void)
-      WEAK_IMPORT_ATTRIBUTE;
-}
-#endif
-
 // We need to provide wrappers around all the libc functions.
 namespace {
 size_t mz_size(malloc_zone_t* zone, const void* ptr) {
@@ -248,13 +235,8 @@
   // doing tiny and small allocs.  Sadly, it assumes that the default
   // zone is the szone implementation from OS X and will crash if it
   // isn't.  By creating the zone now, this will be true and changing
-  // the default zone won't cause a problem.  This only needs to
-  // happen when actually running on OS X 10.6 and higher (note the
-  // ifdef above only checks if we were *compiled* with 10.6 or
-  // higher; at runtime we have to check if this symbol is defined.)
-  if (malloc_default_purgeable_zone) {
-    malloc_default_purgeable_zone();
-  }
+  // the default zone won't cause a problem.  (OS X 10.6 and higher.)
+  malloc_default_purgeable_zone();
 #endif
 
   // Register the tcmalloc zone. At this point, it will not be the