bgfx: Move bgfx config to its own directory

cmake/bgfx/CMakeLists.txt

@@ -0,0 +1,11 @@
+# bgfx.cmake - bgfx building in cmake
+# Written in 2017 by Joshua Brookover <joshua.al.brookover@gmail.com>
+#
+# To the extent possible under law, the author(s) have dedicated all copyright
+# and related and neighboring rights to this software to the public domain
+# worldwide. This software is distributed without any warranty.
+#
+# You should have received a copy of the CC0 Public Domain Dedication along with
+# this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+include(bgfx.cmake)