pick up udev/rules.d/90-xhc.rules debian/linuxcnc.files entry

Missed in merge of commit 026b112c2023ee149a042fb5ba2d0a3def47eff9

Fixes #92
tests/bitops.0/test.sh:  change include dir to /include from /src/rtapi

Theory:  tests ought not to depend on anything in /src/
configure.in:  ensure /bin and /usr/bin are in $PATH

Yes, /bin was actually missing from $PATH in a Wheezy debootstrap
chroot environment.
debian/control.in:  Build-Depends: kmod, procps

If ./configure doesn't find lsmod, ps and kill, the realtime and
linuxcnc scripts will break with empty $LSMOD, $PS and $KILL
variables.
FIXME:  temp. don't kill realtime.in to debug a msgd hang

Instead get a gdb back trace and then hang forever.