Reintroducing MallocHooks changes with fix for hooks being called when in execvpe after a fork whil…

runtime/BUILD.gn

Index: runtime/BUILD.gn
diff --git a/runtime/BUILD.gn b/runtime/BUILD.gn
index 36983b6a75caede18bcd48379045163686f254f8..a70b6b27be408938912d2e3bdfc7effbe740a094 100644
--- a/runtime/BUILD.gn
+++ b/runtime/BUILD.gn
@@ -2,6 +2,8 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
+import("runtime_args.gni")
+
 declare_args() {
   # Instead of using is_debug, we introduce a different flag for specifying a
   # Debug build of Dart so that clients can still use a Release build of Dart
@@ -146,6 +148,12 @@ config("dart_config") {
     defines += [ "NDEBUG" ]
   }
 
+  include_dirs = []
+  if (dart_use_tcmalloc) {
+    defines += [ "DART_USE_TCMALLOC" ]
+    include_dirs += [ "../third_party/tcmalloc/gperftools/src" ]
+  }
+
   if (!is_win) {
     cflags = [
       "-Werror",