mailutils: fix build with multiple mariadb outputs

pkgs/tools/networking/mailutils/default.nix

@@ -18,9 +18,6 @@ stdenv.mkDerivation rec {
       */Makefile{.in,.am}
     sed -i 's:/usr/lib/mysql:${libmysqlclient}/lib/mysql:' configure.ac
     sed -i 's/0\.18/0.19/' configure.ac
-    sed -i -e 's:mysql/mysql.h:mysql.h:' \
-           -e 's:mysql/errmsg.h:errmsg.h:' \
-      sql/mysql.c
   '';
 
   nativeBuildInputs = [