loader: Move the wayland protocol build into loader

We can hang this here instead of off wayland-drm's build.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32757>

src/loader/meson.build

@@ -4,6 +4,33 @@
 inc_loader = include_directories('.')
 
 if with_platform_wayland
+  wp_dir = dep_wl_protocols.get_variable(pkgconfig : 'pkgdatadir', internal : 'pkgdatadir')
+  wp_protos = {
+    'fifo-v1': 'staging/fifo/fifo-v1.xml',
+    'commit-timing-v1': 'staging/commit-timing/commit-timing-v1.xml',
+    'linux-dmabuf-unstable-v1': 'unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml',
+    'presentation-time': 'stable/presentation-time/presentation-time.xml',
+    'tearing-control-v1': 'staging/tearing-control/tearing-control-v1.xml',
+    'linux-drm-syncobj-v1': 'staging/linux-drm-syncobj/linux-drm-syncobj-v1.xml',
+    'color-management-v1': 'staging/color-management/color-management-v1.xml',
+  }
+  wp_files = {}
+  foreach name, xml : wp_protos
+    code = custom_target(
+      name + '-protocol.c',
+      input : files(join_paths(wp_dir, xml)),
+      output : name + '-protocol.c',
+      command : [prog_wl_scanner, wl_scanner_arg, '@INPUT@', '@OUTPUT@'],
+    )
+    header = custom_target(
+      name + '-client-protocol.h',
+      input : files(join_paths(wp_dir, xml)),
+      output : name + '-client-protocol.h',
+      command : [prog_wl_scanner, 'client-header', '@INPUT@', '@OUTPUT@'],
+    )
+    wp_files += { name: [code, header] }
+  endforeach
+
   libloader_wayland_helper = static_library(
     'loader_wayland_helper',
     'loader_wayland_helper.c',