Stack buffer for builtin code generation too small in some cases.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index b672185792c417a75f311c7ea6b35d880f91f6a4..f5218d137f50330c17abe286363bd6a6120758c4 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -2094,6 +2094,9 @@ 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