Make it possible to pass GYP_DEFINES to Android builds

platform_tools/android/bin/android_setup.sh

 #!/bin/bash
 #
 # android_setup.sh: Sets environment variables used by other Android scripts.
 
 # Parse the arguments for a DEVICE_ID.
 DEVICE_ID=""
 DEVICE_SERIAL=""
 while (( "$#" )); do
   if [[ $(echo "$1" | grep "^-d$") != "" ]];
   then
@@ skipping 225 matching lines @@
   verbose "The build is targeting the device: $TARGET_DEVICE"
   export DEVICE_ID="$TARGET_DEVICE"
 
   # Set up the toolchain.
   setup_toolchain
   if [[ "$?" != "0" ]]; then
     return 1
   fi
   DEFINES="${DEFINES} android_toolchain=${TOOLCHAIN_TYPE}"
 
-  exportVar GYP_DEFINES "$DEFINES"
+  exportVar GYP_DEFINES "$DEFINES $GYP_DEFINES"
   exportVar SKIA_OUT "out/config/android-${TARGET_DEVICE}"
 }
 
 # adb_pull_if_needed(android_src, host_dst)
 adb_pull_if_needed() {
 
   # get adb location
   source $SCRIPT_DIR/utils/setup_adb.sh
 
   # read input params
@@ skipping 66 matching lines @@
   else
     $ADB $DEVICE_SERIAL push $HOST_SRC $ANDROID_DST
   fi
 }
 
 # Set up the device.
 setup_device "${DEVICE_ID}"
 if [[ "$?" != "0" ]]; then
   exit 1
 fi