www/nginx-acme: fix build with nginx-devel flavor

Fix build failure when building www/nginx-acme against www/nginx-devel
due to an updated ngx_http_validate_host() function signature.

The build previously failed with:

error[E0061]: this function takes 4 arguments but 3 arguments were

supplied

--> src/conf/order.rs:252:28

Apply a flavor-specific patch for the devel flavor only, keeping the
default nginx flavor unchanged.

This restores successful builds for both nginx and nginx-devel flavors.

Sponsored by: Netzkommune GmbH