Fix compilation error

Fix the following warning/error:

    ../app/src/cli.c:2158:17: warning: a label can only be part of a
    statement and a declaration is not a statement [-Wpedantic]

With some compilers, this is an error rather than a pedantic warning.

Refs <https://github.com/Genymobile/scrcpy/issues/2256#issuecomment-1467008307>