Return 0 when we fail to get the amount of system memory on some obscure OS
Currently we incorrectly return -1 when sysctl fails in
#elif defined(HAVE_SYSCTL) && defined(HW_PHYSMEM)
/* On some systems (like FreeBSD I hope) you can use a size_t with
* HW_PHYSMEM. */
size_t memsize=0;
size_t len = sizeof(memsize);
int mib[2] = {CTL_HW, HW_USERMEM};
if (sysctl(mib,2,&memsize,&len,NULL,0))
return -1;
return memsize;