Fix solink and add a postsolink hook (use the hook for android strip)

build/toolchain/android/BUILD.gn

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sysroot.gni")  # Imports android/config.gni.
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
 # The Android GCC toolchains share most of the same parameters, so we have this
@@ skipping 30 matching lines @@
       goma_prefix = ""
     }
 
     cc = goma_prefix + tool_prefix + "gcc"
     cxx = goma_prefix + tool_prefix + "g++"
     ar = tool_prefix + "ar"
     ld = cxx
 
     toolchain_os = "android"
     toolchain_cpu_arch = invoker.toolchain_cpu_arch
+
+    android_strip = "${tool_prefix}strip"
+    mkdir_command = "mkdir -p lib.stripped"
+    strip_command = "$android_strip --strip-unneeded -o lib.stripped/\$soname.tmp \$lib"
+    replace_command = "if ! cmp -s lib.stripped/\${soname}.tmp lib.stripped/\${soname}; then mv lib.stripped/\${soname}.tmp lib.stripped/\${soname}; fi"
+    postsolink = "$mkdir_command && $strip_command && $replace_command"
   }
 }
 
 android_gcc_toolchain("x86") {
   android_ndk_sysroot = "$android_ndk_root/$x86_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$x86_android_toolchain_root/bin/i686-linux-android-"
   toolchain_cpu_arch = "x86"
 }
 
 android_gcc_toolchain("arm") {
   android_ndk_sysroot = "$android_ndk_root/$arm_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$arm_android_toolchain_root/bin/arm-linux-androideabi-"
   toolchain_cpu_arch = "arm"
 }
 
 android_gcc_toolchain("mipsel") {
   android_ndk_sysroot = "$android_ndk_root/$mips_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$mips_android_toolchain_root/bin/mipsel-linux-android-"
   toolchain_cpu_arch = "mipsel"
 }