g10: remove skeleton options files

* build-aux/speed/w32/inst.nsi: stop installing skeleton files.
* doc/gpg.texi: stop documenting skeleton files.
* g10/Makefile.am: stop installing skeleton files.
* g10/openfile.c (copy_options_file): Remove.
(try_make_homedir): do not call copy_options_file()

The defaults for gpg and dirmngr are good. Both programs should work
fine for the simple case without any config file. The skeleton config
files were being copied at first use (when the defaults are fine).
But when the user needs to fiddle with them (after they've become
sophisticated users), they're likely out of date because gpg has been
upgraded since then. So they're used for documentation, but they're
stale documentation, which is probably worse than a clean empty file.

• GnuPG-bug-id: T3086
• Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>