gpg,sm: Ignore the log-file option from common.conf.

* g10/gpg.c (main): Don't use the default log file from common.conf.
* sm/gpgsm.c (main): Ditto.

That was acutally not intended and contradicts the description in
doc/example/common.conf.

• Signed-off-by: Werner Koch <wk@gnupg.org>