BUILD: try to automatically detect the Lua library name

BUILD: try to automatically detect the Lua library name

Depending on the distribution, the Lua library can have different names.
Some distributions will require -llua5.2, others -llua52, and other systems may
require -llua.

Now, the Makefile will try to guess the library name, in order of priority :
"lua5.2", "lua52", or "lua".