devel/lua-language-server: fix build on powerpc*

In file included from 3rd/bee.lua/binding/lua_thread.cpp:2:
In file included from 3rd/bee.lua/bee/thread/lockqueue.h:5:
3rd/bee.lua/bee/thread/spinlock.h:22:6: error: unsupport platform

#error unsupport platform
 ^

3rd/bee.lua/bee/thread/spinlock.h:34:21: error: use of undeclared identifier 'cpu_relax'

cpu_relax();