Bug 1790496 - P2 - add drm moz.build;r=mjf

Differential Revision: https://phabricator.services.mozilla.com/D164033

third_party/drm/libdrm/moz.build

@@ -0,0 +1,19 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    'mozdrm.cpp',
+]
+
+if CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
+    CXXFLAGS += CONFIG['MOZ_GTK3_CFLAGS']
+
+LOCAL_INCLUDES += [
+        '/third_party/drm/',
+        '/third_party/drm/drm/include/libdrm/',
+    ]
+
+FINAL_LIBRARY = 'xul'