[android] Migrate more configs to gyp.

build/standalone.gypi

Index: build/standalone.gypi
diff --git a/build/standalone.gypi b/build/standalone.gypi
index 7984fb3e6066ec2a3a70835137a4fb3332ebcb8f..af23941b1d288d31234f53cb1a871563ec9e67a0 100644
--- a/build/standalone.gypi
+++ b/build/standalone.gypi
@@ -222,31 +222,47 @@
 
           # Copy conditionally-set variables out one scope.
           'android_ndk_root%': '<(android_ndk_root)',
+          'host_os%': '<(host_os)',
 
           'conditions': [
             ['target_arch == "ia32"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/x86-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'x86',
+              'android_target_platform%': '16',
             }],
             ['target_arch == "x64"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/x86_64-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'x86_64',
+              'android_target_platform%': '21',
             }],
             ['target_arch=="arm"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/arm-linux-androideabi-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'arm',
+              'android_target_platform%': '16',
             }],
             ['target_arch == "arm64"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/aarch64-linux-android-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'arm64',
+              'android_target_platform%': '21',
             }],
             ['target_arch == "mipsel"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/mipsel-linux-android-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'mips',
+              'android_target_platform%': '16',
             }],
             ['target_arch == "mips64el"', {
               'android_toolchain%': '<(android_ndk_root)/toolchains/mips64el-linux-android-4.9/prebuilt/<(host_os)-<(android_host_arch)/bin',
+              'android_target_arch%': 'mips64',
+              'android_target_platform%': '21',
             }],
           ],
         },
 
         # Copy conditionally-set variables out one scope.
+        'android_target_arch%': '<(android_target_arch)',
+        'android_target_platform%': '<(android_target_platform)',
         'android_toolchain%': '<(android_toolchain)',
+        'host_os%': '<(host_os)',
 
         'conditions': [
           ['android_ndk_root==""', {
@@ -310,6 +326,11 @@
   'target_defaults': {
     'variables': {
       'v8_code%': '<(v8_code)',
+      'conditions':[
+        ['OS=="android"', {
+          'host_os%': '<(host_os)',
+        }],
+      ],
     },
     'default_configuration': 'Debug',
     'configurations': {