Control profiling/debugger support from build script

src/x64/cfg-x64.cc

Index: src/x64/cfg-x64.cc
===================================================================
--- src/x64/cfg-x64.cc	(revision 2873)
+++ src/x64/cfg-x64.cc	(working copy)
@@ -112,12 +112,14 @@
   __ pop(rbp);
   int count = CfgGlobals::current()->fun()->scope()->num_parameters();
   __ ret((count + 1) * kPointerSize);
+#ifdef ENABLE_DEBUGGER_SUPPORT
   // Add padding that will be overwritten by a debugger breakpoint.
   // "movq rsp, rbp; pop rbp" has length 4.  "ret k" has length 3.
   const int kPadding = Debug::kX64JSReturnSequenceLength - 4 - 3;
   for (int i = 0; i < kPadding; ++i) {
     __ int3();
   }
+#endif
 }