build: Build resources with meson instead of build.rs

Allows us to get rid of build.rs, which was only used to
compile resources. static_resource.rs is now created by
meson, and the meson path is used for include_bytes!.

Closes https://gitlab.gnome.org/World/podcasts/issues/55

podcasts-gtk/src/meson.build

@@ -15,12 +15,29 @@ run_command(
   check: true
 )
 
+# include_bytes! only takes a string literal
+resource_conf = configuration_data()
+resource_conf.set_quoted('RESOURCEFILE', podcasts_resources.full_path())
+resource_rs = configure_file(
+  input: 'static_resource.rs.in',
+  output: 'static_resource.rs',
+  configuration: resource_conf
+)
+
+run_command(
+  'cp',
+  resource_rs,
+  meson.current_source_dir(),
+  check: true
+)
+
 cargo_release = custom_target('cargo-build',
                         build_always_stale: true,
                         output: ['gnome-podcasts'],
                         install: true,
                         install_dir: podcasts_bindir,
                         console: true,
+                        depends: podcasts_resources,
                         command: [cargo_script,
                                   '@SOURCE_ROOT@',
                                   '@OUTPUT@',

podcasts-gtk/src/static_resource.rs.in

@@ -23,7 +23,7 @@ use glib::Bytes;
 pub(crate) fn init() -> Result<(), Error> {
     // load the gresource binary at build time and include/link it into the final
     // binary.
-    let res_bytes = include_bytes!("../resources/resources.gresource");
+    let res_bytes = include_bytes!(@RESOURCEFILE@);
 
     // Create Resource it will live as long the value lives.
     let gbytes = Bytes::from_static(res_bytes.as_ref());