Use $ANDROID_TOOLCHAIN set by envsetup.sh in adb_gdb and gdb_apk

build/android/gdb_apk

 #!/bin/bash
 #
 # Copyright (c) 2012 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.
 #
 # Attach gdb to a running android application.  Similar to ndk-gdb.
 # Run with --annotate=3 if running under emacs (M-x gdb).
 #
 # By default it is used to debug content shell, if it is used to
@@ skipping 140 matching lines @@
 
 # gdb commands
 cmdfile=$(mktemp /tmp/gdb_android_XXXXXXXX)
 cat >$cmdfile<<EOF
 # set solib-absolute-prefix null
 set solib-search-path ${shared_lib_dir}
 file ${app_process}
 target remote :4321
 EOF
 
-gdb=$(echo $ANDROID_TOOLCHAIN/../../linux-x86/bin/*gdb)
+gdb=$(echo $ANDROID_TOOLCHAIN/*gdb)
 if [[ ! -f ${gdb} ]] ; then
   echo "Wow no gdb in env var ANDROID_TOOLCHAIN which is $ANDROID_TOOLCHAIN"
   exit 4
 else
   echo Using $gdb
 fi
 
 # ${gdb} -x $cmdfile $* $app_process
 ${gdb} -x $cmdfile $gdb_args
 rm $cmdfile