build: added another possible name for lua package

On FreeBSD the lua package was not detected. (Tested on 9.3 and 10.1).

Makefile

@@ -19,6 +19,7 @@ $(eval $(call find_lib,libknot))
 $(eval $(call find_lib,libuv))
 $(eval $(call find_alt,lua,luajit))
 $(eval $(call find_alt,lua,lua5.2))
+$(eval $(call find_alt,lua,lua-5.2))
 $(eval $(call find_alt,lua,lua))
 $(eval $(call find_lib,cmocka))
 $(eval $(call find_bin,doxygen))