use -classpath instead of -cp so that jdb can be used for :java-cmd

bin/lein

@@ -287,7 +287,7 @@ else
             -Dfile.encoding=UTF-8 \
             -Dmaven.wagon.http.ssl.easy=false \
             -Dleiningen.original.pwd="$ORIGINAL_PWD" \
-            -cp "$CLASSPATH" \
+            -classpath "$CLASSPATH" \
             clojure.main -m leiningen.core.main "$@"
 
         EXIT_CODE=$?

leiningen-core/src/leiningen/core/eval.clj

@@ -151,8 +151,8 @@
     [(apply str "-Xbootclasspath/a:"
             (interpose java.io.File/pathSeparatorChar
                        (classpath/get-classpath project)))]
-    ["-cp" (string/join java.io.File/pathSeparatorChar
-                        (classpath/get-classpath project))]))
+    ["-classpath" (string/join java.io.File/pathSeparatorChar
+                               (classpath/get-classpath project))]))
 
 (defn shell-command [project form]
   `(~(or (:java-cmd project) (System/getenv "JAVA_CMD") "java")