GN: add a helper script for running Android builds

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 13 matching lines @@
 
 config("no_rtti") {
   if (sanitize != "ASAN") {  # -fsanitize=vptr requires RTTI
     cflags_cc = [ "-fno-rtti" ]
   }
 }
 
 config("default") {
   cflags = [
     "-O1",
-    "-g",
     "-fstrict-aliasing",
     "-fPIC",
     "-fvisibility=hidden",
 
     "-Werror",
     "-Wall",
     "-Wextra",
     "-Winit-self",
     "-Wpointer-arith",
     "-Wsign-compare",
     "-Wvla",
 
     "-Wno-deprecated-declarations",
     "-Wno-unused-parameter",
   ]
   cflags_cc = [
     "-std=c++11",
     "-fno-exceptions",
     "-fno-threadsafe-statics",
     "-fvisibility-inlines-hidden",
 
     "-Wnon-virtual-dtor",
   ]
   ldflags = []
 
+  # It's annoying to wait for full debug symbols to push over
+  # to Android devices.  -gline-tables-only is a lot slimmer.
+  if (is_android) {
+    cflags += [ "-gline-tables-only" ]
+  } else {
+    cflags += [ "-g" ]
+  }
+
   if (current_cpu == "arm") {
     cflags += [
       "-march=armv7-a",
       "-mfpu=neon",
       "-mthumb",
     ]
   } else if (current_cpu == "mipsel") {
     cflags += [
       "-march=mips32r2",
       "-mdspr2",
@@ skipping 151 matching lines @@
   }
 
   tool("stamp") {
     command = "touch {{output}}"
   }
 
   tool("copy") {
     command = "ln -f {{source}} {{output}} 2>/dev/null || (rm -rf {{output}} && cp -af {{source}} {{output}})"
   }
 }