Fix GType on arm64 #51

Job	Run time
windows (lua53, lua5.3, 5.3, /mingw64/include/lua5.3/)	3m 16s
unix (5.1, ubuntu-latest)	38s
windows (lua, lua, 5.4, /mingw64/include/)	3m 14s
unix (5.1, macos-latest)	2m 6s
windows (luajit, luajit, 5.1, /mingw64/include/luajit-2.1/)	3m 11s
unix (5.2, ubuntu-latest)	32s
unix (5.2, macos-latest)	1m 39s
unix (5.3, ubuntu-latest)	40s
unix (5.3, macos-latest)	2m 7s
unix (5.4, ubuntu-latest)	37s
unix (5.4, macos-latest)	1m 57s
unix (luajit-2.1.0-beta3, ubuntu-latest)	33s
unix (luajit-2.1.0-beta3, macos-latest)	1m 39s
unix (luajit-openresty, ubuntu-latest)	36s
unix (luajit-openresty, macos-latest)	1m 34s
	24m 19s

Provide feedback