secret patch: gracefully shutdown bgfx on quit

prevents segfault on exit in Linux

dist/scripts/core/core.t

@@ -118,16 +118,26 @@ function truss.sleep(ms)
   truss.C.sleep(ms)
 end
 
--- gracefully quit truss with an optional error code
-function truss.quit(code)
+-- the true quit function
+local _quit_code
+local function _truss_quit()
+  log.info("Shutdown: calling cleanup functions")
   for _, f in pairs(truss._cleanup_functions) do f() end
-  if code and type(code) == "number" then
-    truss.C.set_error(code)
-    log.info("Error code: [" .. tostring(code) .. "]")
+  if _quit_code and type(_quit_code) == "number" then
+    truss.C.set_error(_quit_code)
+    log.info("Error code: [" .. tostring(_quit_code) .. "]")
   end
   truss.C.stop_interpreter(TRUSS_ID)
 end
 
+-- gracefully quit truss with an optional error code
+function truss.quit(code)
+  log.info("Shutdown requested from Lua")
+  _quit_code = code
+  _core_update = _truss_quit
+  _fallback_update = _truss_quit
+end
+
 -- load an entire file into memory as a string (8-bit clean)
 function truss.load_string_from_file(filename)
   local temp = truss.C.load_file(filename)

dist/scripts/gfx/common.t

@@ -220,6 +220,7 @@ function m.init_gfx(options)
   bgfx.set_debug(debug)
 
   log.info("initted bgfx")
+  truss.on_quit(bgfx.shutdown)
   local backend_type = bgfx.get_renderer_type()
   if options.backend and (backend_type ~= renderer_type) then
     log.warn("Requested backend", options.backend, "is not available!")