Support multiple drives when running CLI using Cygwin

See gh-17872

spring-boot-project/spring-boot-cli/src/main/executablecontent/bin/spring

@@ -18,7 +18,7 @@ case "$(uname)" in
 esac
 
 # For Cygwin, ensure paths are in UNIX format before anything is touched.
-if ${cygwin} ; then
+if $cygwin ; then
 	[ -n "${JAVA_HOME}" ] && JAVA_HOME=$(cygpath --unix "${JAVA_HOME}")
 fi
 
@@ -99,12 +99,14 @@ if [ ! -d "${SPRING_HOME}" ]; then
 	exit 2
 fi
 
-CLASSPATH=.:${SPRING_HOME}/bin
-if [ -d "${SPRING_HOME}/ext" ]; then
-	CLASSPATH=$CLASSPATH:${SPRING_HOME}/ext
+[[ $cygwin ]] && SPRINGPATH=$(cygpath "${SPRING_HOME}") || SPRINGPATH=$SPRING_HOME
+CLASSPATH=.:${SPRINGPATH}/bin
+if [ -d "${SPRINGPATH}/ext" ]; then
+	CLASSPATH=$CLASSPATH:${SPRINGPATH}/ext
 fi
-for f in "${SPRING_HOME}"/lib/*; do
-	CLASSPATH=$CLASSPATH:$f
+for f in "${SPRINGPATH}"/lib/*; do
+	[[ $cygwin ]] && LIBFILE=$(cygpath "$f") || LIBFILE=$f
+	CLASSPATH=$CLASSPATH:$LIBFILE
 done
 
 if $cygwin; then