Merge branch 'maint'

Two fixes for gcc-12 warnings, and another fix for a benign but
embarrassing braino in gcrypt.c.

* maint:
  gcrypt: Fix return value of apc_get_pubkey().
  error.h: Be more careful with error code masking.
  mp3_afh: Drop unused fields from struct mp3header.

diff --cc crypt.h
Simple merge

diff --cc error.h
Simple merge

diff --cc gcrypt.c
Simple merge

diff --cc mp3_afh.c
Simple merge