v8: pull fix for builtin code size on PPC

Pull in the change that has been committed to v8 master in
https://codereview.chromium.org/1415463002/.  We are currently
cherry-picking into 4.6 and 4.7 but until next next v8 update
into Node Master I'd like to float it as it will make PPC LE
go green in the CI

Fixes: #3390
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <ben@strongloop.com>
PR-URL: #3474

Author: mhdawson

deps/v8/src/builtins.cc

@@ -1531,6 +1531,9 @@ void Builtins::SetUp(Isolate* isolate, bool create_heap_objects) {
 #ifdef DEBUG
   // We can generate a lot of debug code on Arm64.
   const size_t buffer_size = 32*KB;
+#elif V8_TARGET_ARCH_PPC64
+  // 8 KB is insufficient on PPC64 when FLAG_debug_code is on.
+  const size_t buffer_size = 10 * KB;
 #else
   const size_t buffer_size = 8*KB;
 #endif