I want to be able to switch dev machines without having to uninstall

the latest debug build from my phones, and that requires using the
same debug.keystore everywhere. So check one in, and add a script that
symlinks to it from the machine's global location if necessary.

xwords4/android/scripts/common_targets.xml

@@ -16,6 +16,9 @@
     </target>
 
     <target name="my-pre-build">
+      <exec dir="." executable="../scripts/key-setup.sh"
+            failonerror="true"
+            />
         <exec dir="." executable="../scripts/ndksetup.sh" output="/dev/null"
               failonerror="true">
             <arg value="${build.target}"/>

xwords4/android/scripts/key-setup.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+set -e -u
+
+HOMELOC=~/.android/debug.keystore
+HERELOC=$(pwd)/$(dirname $0)/debug.keystore
+# SCRIPTS=
+
+if [ -L $HOMELOC ]; then 
+	if cmp $(readlink $HOMELOC) $HERELOC; then
+		exit 0
+	fi
+elif [ -e $HOMELOC ]; then
+	cat << EOF
+* You are using a different keystore from what's part of this project.
+* You won't be able to install this over something built from a
+* different machine.  If that's not ok, remove it (i.e. run this on a
+* commandline: 
+rm $HOMELOC
+* and rerun ant to use the built-in keystore.
+EOF
+else
+	echo "$0: creating link at $HOMELOC"
+	ln -sf  $HERELOC $HOMELOC
+fi