lib/curl_path.c: add ISC to license expression

THe text of the ISC license is in this file, so the SPDX license
expression should be updated

Closes #9073

lib/curl_path.c

@@ -18,7 +18,7 @@
  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  * KIND, either express or implied.
  *
- * SPDX-License-Identifier: curl
+ * SPDX-License-Identifier: curl AND ISC
  *
  ***************************************************************************/