main/musl: fix error handling in getsubopt
This fixes a segfault in argument parsing e.g. when running v4l2-ctl -c focus_auto=0.
Patch submitted for upstreaming: https://www.openwall.com/lists/musl/2021/11/03/1
This fixes a segfault in argument parsing e.g. when running v4l2-ctl -c focus_auto=0.
Patch submitted for upstreaming: https://www.openwall.com/lists/musl/2021/11/03/1