Fix find-jdk-tools-jar to be cygwin-friendly.

Change-Id: I9cf2035026725fd1ba8a014b484262ed1acc1df4
diff --git a/core/find-jdk-tools-jar.sh b/core/find-jdk-tools-jar.sh
index f555576..20d7d4d 100755
--- a/core/find-jdk-tools-jar.sh
+++ b/core/find-jdk-tools-jar.sh
@@ -6,9 +6,9 @@
 	echo "Please-install-JDK-6,-which-you-can-download-from-java.sun.com"
 	exit 1
     fi
-    while [ -L $JAVAC ] ; do
-        LSLINE=$(ls -l $JAVAC)
-        JAVAC=$(echo -n $LSLINE | sed -e "s/.* -> //")
+    while [ -L "$JAVAC" ] ; do
+        LSLINE=$(ls -l "$JAVAC")
+        JAVAC=$(echo -n "$LSLINE" | sed -e "s/.* -> //")
     done
     echo $JAVAC | sed -e "s:\(.*\)/bin/javac.*:\\1/lib/tools.jar:"
 fi