approaching 4.5.21 release

[Mike Frysinger]

vm is back up.  testing e44a4a262ab1d47815262a6bb03ba6001c79096a:
s390: ok
s390x: hangs hard too, but merging ldv/PTRACE_GETEVENTMSG fixes it

so at this point, i think the only ones not tested:
 - avr32
 - microblaze
 - mips
 - sh64 (although i think this is more PoC?  ive never seen anyone
running 64bit on SuperH ...)
 - tile

i dont have ready access to any of these atm, and that wont change anytime soon.
-mike