The vast majority of invocations of `ot_gpgme_error_to_gio_error()` were paired
with `g_prefix_error()`; let's combine them for the same reason we do
`glnx_throw_errno_prefix()`. For the few cases that don't we might as well add
some prefix.
I also changed it to `return FALSE` in prep for more style porting.
Closes: #1135
Approved by: jlebon
Prep for dropping `GLNX_DEFINE_CLEANUP_FUNCTION` from libglnx
in favor of using GLib's `G_DEFINE_AUTO_CLEANUP_FREE_FUNC()`.
Closes: #1042
Approved by: jlebon
The keyring isn't large, so let's just fall back to copying it
rather than requiring `renameat()`.
Prep for `ostree_repo_open_at()`.
Closes: #821
Approved by: jlebon
Colin Walters
Matthew Barnes