Compile Release builds with -momit-leaf-frame-pointer.

Unlike -fomit-frame-pointer, this doesn't make debugging or profiling any more difficult, as it only applies to leaves.  It will make our code (negligibly) smaller and (negligibly) faster.

Mostly I just find it easier to read the disassembly without all the rbp gymnastics getting in the way.


BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3700

Change-Id: I4b96aee7619791d5980de7f46e82836ca08a6456
Reviewed-on: https://skia-review.googlesource.com/3700
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 5d6a82a..24807d8 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -331,7 +331,10 @@
   if (is_win) {
     cflags = [ "/O2" ]
   } else {
-    cflags = [ "-O3" ]
+    cflags = [
+      "-O3",
+      "-momit-leaf-frame-pointer",
+    ]
   }
   defines = [ "NDEBUG" ]
 }