Merge branch 'bt/gpg-interface'
What is queued here is only the obviously correct and
uncontroversial code clean-up part, which is an earlier 7 patches,
of a larger series.
The remainder that is not queued introduces a few configuration
variables to deal with e-signature backends with different
signature format.
* bt/gpg-interface:
gpg-interface: find the last gpg signature line
gpg-interface: extract gpg line matching helper
gpg-interface: fix const-correctness of "eol" pointer
gpg-interface: use size_t for signature buffer size
gpg-interface: modernize function declarations
gpg-interface: handle bool user.signingkey
t7004: fix mistaken tag name