O_NOFOLLOW would be very nice to have here if the version of linux
we are running supports it.
from enh@google.com
Possibly obtain a little bit of entropy from addresses returned
by getauxval if we have it.
ok deraadt@
comment fixes from theo
get the page of data at AT_SYSINFO_EHDR
ok deraadt@
AT_BASE returns us the *address* of the start of ld.so, so
use the address, not what it points to (which is always the same)
ok deraadt@