build: add -zip option to macdeployqtplus

This zips the app bundle in /dist.

contrib/macdeploy/macdeployqtplus

@@ -397,6 +397,7 @@ ap.add_argument("-no-plugins", dest="plugins", action="store_false", default=Tru
 ap.add_argument("-no-strip", dest="strip", action="store_false", default=True, help="don't run 'strip' on the binaries")
 ap.add_argument("-dmg", nargs="?", const="", metavar="basename", help="create a .dmg disk image")
 ap.add_argument("-translations-dir", nargs=1, metavar="path", default=None, help="Path to Qt's translations. Base translations will automatically be added to the bundle's resources.")
+ap.add_argument("-zip", nargs="?", const="", metavar="zip", help="create a .zip containing the app bundle")
 
 config = ap.parse_args()
 
@@ -593,6 +594,11 @@ if config.dmg is not None:
 
 # ------------------------------------------------
 
+if config.zip is not None:
+    shutil.make_archive('{}'.format(appname), format='zip', root_dir='dist', base_dir='Bitcoin-Qt.app')
+
+# ------------------------------------------------
+
 print("+ Done +")
 
 sys.exit(0)