meson: handle dep_libdrm before the driver specific libdrm modules

Handle dep_libdrm before the driver specific libdrm modules, this is for
when libdrm is built as a subproject, for example libdrm_amdgpu is only
available after dep_libdrm has been added.

Acked-by: Valentine Burley <valentine.burley@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36710>

meson.build

@@ -1691,20 +1691,6 @@ endif
 
 allow_fallback_for_libdrm = get_option('allow-fallback-for').contains('libdrm')
 
-# Then get each libdrm module
-foreach d : _libdrm_checks
-  if d[1]
-    set_variable(
-      'dep_libdrm_' + d[0],
-      dependency(
-        'libdrm_' + d[0],
-        version : '>=' + _drm_ver,
-        allow_fallback: allow_fallback_for_libdrm,
-      )
-    )
-  endif
-endforeach
-
 with_gallium_drisw_kms = false
 if system_has_kms_drm
   dep_libdrm = dependency(
@@ -1724,6 +1710,20 @@ if dep_libdrm.found()
   endif
 endif
 
+# Then get each libdrm module
+foreach d : _libdrm_checks
+  if d[1]
+    set_variable(
+      'dep_libdrm_' + d[0],
+      dependency(
+        'libdrm_' + d[0],
+        version : '>=' + _drm_ver,
+        allow_fallback: allow_fallback_for_libdrm,
+      )
+    )
+  endif
+endforeach
+
 dep_libudev = dependency('libudev', required : false)
 if dep_libudev.found()
   pre_args += '-DHAVE_LIBUDEV'