gptfdisk: fix stack overflow in parsing cmdline

The getopt_long will return -1 when all command-line
options have been parsed, and the index value will not
be changed in that case.

The caller should check both and handle it properly.

BUG: 64235252

Change-Id: I203dd5bc42bb7ce83e558f25074c7e1a92f250e9

(cherry picked from commit 69e46b9a1cd70aa92fefb3d7a8738c6876df4659)
1 file changed