fix script so that the error is actually printed if ant is not installed

R=scroggo@google.com, hcm@google.com

Author: djsollen@google.com

Review URL: https://codereview.chromium.org/148793003

git-svn-id: http://skia.googlecode.com/svn/trunk@13290 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/platform_tools/android/bin/android_setup.sh b/platform_tools/android/bin/android_setup.sh
index 9dc92f6..7a44317 100755
--- a/platform_tools/android/bin/android_setup.sh
+++ b/platform_tools/android/bin/android_setup.sh
@@ -54,7 +54,7 @@
 fi
 
 # ant is required to be installed on your system and in your PATH
-ant -version &> /dev/null
+which ant &> /dev/null
 if [[ "$?" != "0" ]]; then
   echo "ERROR: Unable to find ant. Please install it before proceeding."
   exit 1