Remove redundant dependency on pkg-config for mariadb.

Author: paurkedal

packages/mariadb/mariadb.1.3.0/opam

@@ -21,7 +21,6 @@ depends: [
   "ctypes" {>= "0.13.0"}
   "conf-mariadb"
   "conf-gcc"
-  "conf-pkg-config"
   "dune" {>= "3.15.0"}
   "dune-configurator"
   "async" {with-test}