Log Message:
Fix bootstrap on QNX

Tested with QNX 6.5.0SP1.

Two things were needed:

 * bootstrap needs to export ACCEPT_INFERIOR_RM_PROGRAM=yes on QNX,
   because libarchive checks for "rm -f" (with no arguments) working in
   configure. It doesn't seem to actually use it during the build, so
   this works.
 * QNX.sys.mk sets LORDER to echo, but sets TSORT to tsort -q. This
   results in tsort complaining about having an uneven number of inputs,
   since of course there are no dependency pairs.
   Hence, if LORDER is overridden to echo, TSORT also needs to be
   overridden to cat. Interestingly, Linux.sys.mk also sets LORDER=echo
   and TSORT=tsort -q, so it's surprising this isn't broken as well?