Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Migrate tools/regression/usr.bin/pkill to the new tests layout.

Interestingly, the pkill tool lives in bin, not usr.bin. Haven't bothered
to check if this is because the tool moved or because the tests were
originally added in the wrong place.

Fix pkill tests so that they run cleanly with prove.

This fixes a pgrep test that assumed that PID 2 was named g_event. This
does not seem to be the case any longer (and I don't know if it ever was
in all possible setups).

Change this test to use the idle loop instead and determine its expected
PID using ps without assuming any specific ID.

Purge some useless mergeinfo.

Rename files that collide on case-insensitive file systems by encoding
colliding upper case letters as the lower case letter with a '_' in
front.

MFC after: 3 days
Discussed with: ed
Spotted by: Michael David Crawford <mdc at prgmr.com>

Add regression tests for pkill/pgrep.

MFC after: 3 days