Fix default path to pkgconfig files.

--- src/gpgrt-config.in.orig	2024-04-24 04:08:07 UTC
+++ src/gpgrt-config.in
@@ -460,7 +460,7 @@ determine_gpgrt_libdir () {
     # Get the prefix of gpgrt-config assuming it's something like:
     #   <PREFIX>/bin/gpgrt-config
     gpgrt_prefix=${GPGRT_CONFIG%/*/*}
-    possible_libdir1=${gpgrt_prefix}/lib
+    possible_libdir1=${gpgrt_prefix}/libdata
     # Determine by using system libdir-format with CC, it's like:
     #   Normal style: /usr/lib
     #   GNU cross style: /usr/<triplet>/lib