Warnings when compiling the Lua 5.3.5 interpreter by gcc version 7.4.0

[Dirk Laurie <dirk.laurie@...>]

I can't remember that this happened in 2017, but 'make linux' now gives:

lua.c: In function ‘runargs’:
lua.c:531:31: warning: passing argument 2 of ‘dolibrary’ discards
‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
                : dolibrary(L, extra);
                               ^~~~~
lua.c:259:12: note: expected ‘char *’ but argument is of type ‘const char *’
 static int dolibrary (lua_State *L, char *name) {
            ^~~~~~~~~