[PATCH] Make configure work with gpgme >= 1.18

[PATCH] Make configure work with gpgme >= 1.18

Sam James wrote:
> gpgme-1.18.0 dropped a bunch of internal symbols,
> including progress_callback (see e.g. callbacks.h
> which has a comment at the top saying it's internal).

Plausibly the workaround to not link against older KDE-specific distro
packages is not needed anymore.

Check for main as a workaround as we do for other C++ libraries, too.

Change-Id: I57065a5b5b23b9eadb73b01e4f3a289552c3bde4

Gbp-Pq: Name Make-configure-work-with-gpgme-1.18.patch