Copy lib/lua-$(VERSION)/src/liblua.h to lib/lua/ rather than lib/.
Instead of copying any of the header files or telling the compiler
where to find the lua ones, generate include/nhlua.h on the fly and
restrict the knowledge of where they are to it (paths are relative
to include/).
|/* nhlua.h - generated by top Makefile */
|#include "../lib/lua-5.3.5/src/lua.h"
|LUA_API int (lua_error) (lua_State *L) NORETURN;
|#include "../lib/lua-5.3.5/src/lualib.h"
|#include "../lib/lua-5.3.5/src/lauxlib.h"
|/*nhlua.h*/
This might need to be redone (or augmented by having CFLAGS add back
'-I path-to-lua') if some compiler can't find '#include "luaconf.h"'
issued by lua.h.