Add build configuration variable 'c_frame_pointers' to control whether or not frame pointers are in…

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index cf0ff5ec6e46d22cae3b6b15e6231ba9b7f6bfc0..7c1980172931214b3a974397dcb171f4c6bf2244 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -34,8 +34,13 @@ DEFINE_FLAG(int, profile_period, 1000,
             "Time between profiler samples in microseconds. Minimum 50.");
 DEFINE_FLAG(int, profile_depth, 8,
             "Maximum number stack frames walked. Minimum 1. Maximum 255.");
+#if defined(PROFILE_NATIVE_CODE)
+DEFINE_FLAG(bool, profile_vm, true,
+            "Always collect native stack traces.");
+#else
 DEFINE_FLAG(bool, profile_vm, false,
             "Always collect native stack traces.");
+#endif
 
 bool Profiler::initialized_ = false;
 SampleBuffer* Profiler::sample_buffer_ = NULL;