gpg-error.m4: Find gpgrt_libdir by CC.

Authored by gniibe on Nov 2 2018, 1:49 AM.

Description

gpg-error.m4: Find gpgrt_libdir by CC.

* src/gpg-error.m4 (gpgrt_libdir): New.  Bump the version date.
* src/gpgrt.m4: Likewise.

Locating gpg-error.pc file, when it's not found at target's $libdir,
try system libdir defined by CC, assuming CC supports gcc compatible
-print-file-name option.

  • GnuPG-bug-id: T4239
  • Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>