GN: release -> -O3, to match GYP

gn/BUILD.gn

 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 declare_args() {
   ar = "ar"
   cc = "cc"
   cxx = "c++"
 
@@ skipping 87 matching lines @@
       libs += [ "unwind" ]
     }
   }
 
   if (is_linux) {
     libs = [ "pthread" ]
   }
 }
 
 config("release") {
-  cflags = [ "-Os" ]
+  cflags = [ "-O3" ]
   defines = [ "NDEBUG" ]
 }
 
 config("executable") {
   if (is_mac) {
     ldflags = [ "-Wl,-rpath,@loader_path/." ]
   } else if (is_linux) {
     ldflags = [ "-Wl,-rpath,\$ORIGIN" ]
   }
 }
@@ skipping 70 matching lines @@
   }
 
   tool("stamp") {
     command = "touch {{output}}"
   }
 
   tool("copy") {
     command = "ln -f {{source}} {{output}} 2>/dev/null || (rm -rf {{output}} && cp -af {{source}} {{output}})"
   }
 }