Merge #63547: luaPackages.luadbi-mysql: Fix linking issue

Fixes the prosody test, and it seems very unlikely to break anything.

pkgs/development/lua-modules/overrides.nix

@@ -137,8 +137,9 @@ with super;
 
   luadbi-mysql = super.luadbi-mysql.override({
     extraVariables = ''
-      -- Can't just be /include, unfortunately
+      -- Can't just be /include and /lib, unfortunately needs the trailing 'mysql'
       MYSQL_INCDIR='${pkgs.mysql.connector-c}/include/mysql';
+      MYSQL_LIBDIR='${pkgs.mysql.connector-c}/lib/mysql';
     '';
     buildInputs = [
       pkgs.mysql.client