doctor: use -V for python version

`python --version` doesn't work in some (very) old versions of
python. While I doubt this is going to come up very often, it's
theoretically possible someone has an old python first in their
path. (python -V works on all versions I'm aware of, including
python3, and comes before --version in the --help anyway.)

Also skips the warning in case the regexp matches nothing, which
probably shouldn't happen. But if it does we shouldn't produce the
wrong warning.
Define Symbol#to_proc for Ruby 1.8.6

Ruby 1.8.6 doesn't have Symbol#to_proc, which allows things like
map(&:to_s) rather than map { |o| o.to_s }. 1.8.7 does, though, and
since it is used in a bunch of the superenv code we should attempt to
keep it compatible with 1.8.6.

Closes #16046.
mpssh: source download from github
PowerDNS Authoritative Server 3.1.

Closes #14627.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
Rename formula
New Formula: libuv

Closes #16867.

Signed-off-by: Charlie Sharpsteen <source@sharpsteen.net>
byobu 5.24

Closes #16968.
lcov: fix inreplace warnings

Closes #16963.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
Don't store test Proc if we might need to marshall the formula

Procs cannot be marshalled, but formula objects may be as part of the
BuildError exception. If the formula object has a reference to a Proc,
this will fail.

Work around it by not storing the test Procs during installations.
More robust way to avoid attempting to marshal Procs
liblqr 0.4.2
aws-elasticbeanstalk 2.3

Closes #16973.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>