gpgconf: Fix argv overflow if --homedir is used.

* tools/gpgconf-comp.c (gc_component_launch): Fix crash due to too
small array.

Depending on the stack layout this could have led to zeroing out the
PID variable if --homedir was used and thus under Windows to a leaked
handle. However, gpgconf is a short running process and thus no
really harm.

• GnuPG-bug-id: T5366
• Co-authored-by: cbiedl@gnupg.com
• Signed-off-by: Werner Koch <wk@gnupg.org>