Option '-l' discards version sufix from file name

Like 'require', the command-line option '-l' discards an optional
version suffix (everything after an hyphen) from a file name when
creating the module name.

loadlib.c

@@ -24,15 +24,6 @@
 #include "lualib.h"
 
 
-/*
-** LUA_IGMARK is a mark to ignore all before it when building the
-** luaopen_ function name.
-*/
-#if !defined (LUA_IGMARK)
-#define LUA_IGMARK		"-"
-#endif
-
-
 /*
 ** LUA_CSUBSEP is the character that replaces dots in submodule names
 ** when searching for a C loader.