mariadb: disable auth_pam plugin on darwin

Fixes #69034

This plugin doesn’t work right for us now, needs to be disabled. It
was added first in 10.3.18:

91fdb931fa (diff-7cea40646c6b8df9a67a3eac4eec9bc6)

pkgs/servers/sql/mariadb/default.nix

@@ -48,6 +48,9 @@ common = rec { # attributes common to both builds
 
   prePatch = ''
     sed -i 's,[^"]*/var/log,/var/log,g' storage/mroonga/vendor/groonga/CMakeLists.txt
+  '' + optionalString stdenv.hostPlatform.isDarwin ''
+    substituteInPlace cmake/build_configurations/mysql_release.cmake \
+      --replace "SET(PLUGIN_AUTH_PAM YES)" ""
   '';
 
   patches = [