fix build error message

cordova/makefile.am

@@ -29,10 +29,13 @@ ${ANDROID}: ${ANDROID_SRC}
 	fi
 
 clean-local:
-	platforms/android/cordova/clean
+	-platforms/android/cordova/clean
+
+distclean-local:
 	-rm -r platforms/android/.gradle
 	for file in ${cordova_sources}; do \
 	  if test "@srcdir@/$${file}" != "$${file}" \
+	          -a -f "$${file}" \
                   -a "@srcdir@" != "." \
                   -a "@srcdir@" != "./"; then \
 	      chmod -R u+w "$${file}" && rm -r "$${file}"; \