gpgconf: Ignore non-installed components with --apply-profile.

* tools/gpgconf-comp.c (retrieve_options_from_program): Add arg
only_installed.
(gc_component_retrieve_options): Use this if we want to process all
components.

Note that this also also ignores them in --with-defaults. This is
useful for systems which come without scdaemon.

• GnuPG-bug-id: T3313
• Signed-off-by: Werner Koch <wk@gnupg.org>