Use of math.huge on 64bit Linux

[Sean Conner <sean@...>]

  Okay, I'm using Lua 5.1.5 (and all the patches [1]) and for the life of
me, I can't figure out what I'm doing wrong.  I have this script:

	proc = require "org.conman.process" -- [2]
	print(math.huge)
	proc.limits.soft.core = math.huge
	print(proc.limits.soft.core)

  On 32-bit Linux, the output is as expected:

	inf
	inf

  But on two different 64-bit Linux systems, I get:

	inf
	0

  I'm not seeing any obvious issues with the function [3].  I traced into
the function, and after it executes:

	ival = lua_tonumber(L,3);

ival is 0, when it should be HUGE_VAL (which on Linux, prints out as 'inf'). 
Tracing into lua_tonumber() doesn't reveal anything, so next, write a
simplified test program to hopefully isolate the issue:

#include <stdio.h>
#include <lua.h>
#include <lauxlib.h>

static int huge(lua_State *L)
{
  lua_Number ival;
  
  if (lua_isnumber(L,1))
    ival = lua_tonumber(L,1);
  else
    return 0;
  
  printf("%f\n",ival);
  return 0;
}

int luaopen_huge(lua_State *L)
{
  lua_pushcfunction(L,huge);
  return 1;
}

And the following script:

	huge = require "huge"
	huge(math.huge)
	huge(0)

Running this on both 64-bit systems, the output is:

	inf
	0

which is *NOT* what I expected (and is, in fact, correct).  So obviously, I
haven't isolated the issue, but I'm not just seeing what could be going
wrong.  I don't think it's because of the fact that I compiled everything
into a custom Lua interpreter with all the modules built in, because I built
in the above module and it still worked.

  I'm missing something obvious and I'm not seeing it.

  -spc (Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah!)

[1]	http://www.lua.org/bugs.html#5.1.5

[2]	https://github.com/spc476/lua-conmanorg/blob/master/src/process.c

[3]	https://github.com/spc476/lua-conmanorg/blob/master/src/process.c#L1184