fix new state crash

[flier]

golua will crash when C.luaL_newstate failed, because LuaJIT has hard limited to 1G memory space.

package main

import (
	"github.com/aarzilli/golua/lua"
	"gopkg.in/cheggaaa/pb.v1"
)

func main() {
	count := 100000
	bar := pb.StartNew(count)
	for i := 0; i < count; i++ {
		bar.Increment()
		if L := lua.NewState(); L != nil {
			L.OpenLibs()
			defer L.Close()
		} else {
			bar.FinishPrint("new state failed")
			break
		}
	}
}

fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x7fff04c4fb80]

runtime stack:
runtime.throw(0x4106c4b, 0x2a)
/usr/local/opt/go/libexec/src/runtime/panic.go:596 +0x95
runtime.sigpanic()
/usr/local/opt/go/libexec/src/runtime/signal_unix.go:274 +0x2db

goroutine 1 [syscall, locked to thread]:
runtime.cgocall(0x40c52b0, 0xc420474e80, 0x41069de)
/usr/local/opt/go/libexec/src/runtime/cgocall.go:131 +0xe2 fp=0xc420474e40 sp=0xc420474e00
github.com/aarzilli/golua/lua._Cfunc_clua_setgostate(0x0, 0xc4206c8580)
github.com/aarzilli/golua/lua/_obj/_cgo_gotypes.go:431 +0x45 fp=0xc420474e80 sp=0xc420474e40
github.com/aarzilli/golua/lua.newState.func1(0x0, 0xc4206c8580)
/Users/flier/gocode/src/github.com/aarzilli/golua/lua/lua.go:39 +0x6a fp=0xc420474eb8 sp=0xc420474e80
github.com/aarzilli/golua/lua.newState(0x0, 0x3d59)
/Users/flier/gocode/src/github.com/aarzilli/golua/lua/lua.go:39 +0x154 fp=0xc420474f30 sp=0xc420474eb8
github.com/aarzilli/golua/lua.NewState(0xc4200a4280)
/Users/flier/gocode/src/github.com/aarzilli/golua/lua/lauxlib.go:169 +0x2f fp=0xc420474f50 sp=0xc420474f30
main.main()
/Users/flier/NexusGuard/Source/nxgw-engine/luavm.go:13 +0x56 fp=0xc420474f88 sp=0xc420474f50
runtime.main()

[glycerine]

I'm getting this same crash still, on darwin, go1.9.1. I tried both 64-bit and 32-bit builds. go test -v results in crashes for me.

I'll open a separate issue for it.

[glycerine]

#63