gpg: Relax printing of STATUS_FAILURE.

* g10/gpg.c (g10_exit): Print STATUS_FAILURE only based on passed
return code and not on the presence of any call to log_error.

This fixes an actual regression in GPGME where FAILURE is considered
for example by a signature verify operation. The operation will simply
fail and not just record that that a signature could not be verified.
In particular for files with more than one signature a log_error if
often called to show that a pubkey is missing for one of the
signatures. Using that log_error is correct in that case.

• Fixes-commit: 0336e5d1a7b9d46e06c838e6a98aecfcc9542882
• Signed-off-by: Werner Koch <wk@gnupg.org>