as erik quanstro suggests, theres not much of a point in
storing the full 64bit pc as one cannot get a code segment
bigger than 4G and amd64 makes it hard to use a pc that
isnt 64bit sign extension of 32bit.
instead, we only store ulong (as originally), but sign
extend back when returning in getmalloctag() and
getrealloctag().
getrealloctag() used to be broken. its now fixed.
use resrcwait() when waiting for memory to become available. randomize
the sleep time and properly restore old process status in case tsleep()
gets interrupted.
