SMP - clock calibration spurious IRQ deadlock fix

 - this patch fixes a deadlock which may occur if we get a
   spurious interrupt while calibrating clocks during the boot
   time. Since we never handle interrupts while in the kernel
   (BKL locked) the interrupt code locks the lock. This is a
   different situation, a corner case, boot time only. We do not
   return to userspace but to the kernel, so the BKL is not
   unlocked. So we need irq handler which leaves the BKL
   unlocked.  The clock handler does it already, this patch adds
   a dummy spurious irq handler for the same reason. It is better
   to handle the situation this way to keep the normal runtime
   code simple.
Prevent the ramdisk makefile from failing if the last image is not ELF
PM: extend srv_fork to set a specific UID

Currently, all servers and drivers run as root as they are forks of
RS. srv_fork now tells PM with which credentials to run the resulting
fork. Subsequently, PM lets VFS now as well.

This patch also fixes the following bugs:
 - RS doesn't initialize the setugid variable during exec, causing the
   servers and drivers to run setuid rendering the srv_fork extension
   useless.
 - PM erroneously tells VFS to run processes setuid. This doesn't
   actually lead to setuid processes as VFS sets {r,e}uid and {r,e}gid
   properly before checking PM's approval.
AVFS: initialize root FS before receiving new work
AVFS: make forbidden check for specific proc instead of fp
APFS: drop privileges upon startup

Move SERVICE_LOGIN to rs.h global header so it's accessible for all.
INET: drop privileges upon startup
Add permission test for bind and socket

Also, apply forbidden patch to VFS from AVFS (fixes hanging test56 if
it has the permission test).
Don't panic on a misconfigured machine
INET: remove erroneous assert

The queue may contain established connections which have
tc_connInprogress clear.
e1000: reset hardware before stopping
service: allow starting service with user's realuid
AVFS: only put mount point when it was used as one

When a mount operation fails and the FS exits, free_proc could try and
clean up resources associated with the mount point before the mount
thread itself can do that. However, the clean up procedure should only
clean up resources that were actually in use.
libpuffs: make GCC happy
INET: fix a few GCC compilation warnings
Remove unused variables
INET: fix 'improved' assert
APFS: fix link issue when compiling with Clang
temporarily disable update-superblock check

	. incompatible with installboot -d FSDEV on mounted filesystems
	. should be re-enabled when netbsd boot loader is default
inet: strncmp() fix