Guess system XQuartz version when mdfind fails

Fixes #16857.
gtk+: relax X11 dependency version

2.6.3 was chosen because Leopard's system X11 (2.1.6) is too old to
build gtk+, and it was the most recent version that is compatible with
Leopard. There are now reports that Snow Leopard's system X11 (2.3.6)
can build this, so relax the requirement.

c.f. #15928.
moreutils and task-spooler conflict

Fixes #16850.
youtube-dl 2013.01.02

Closes #16866.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
opam-0.8.3

Closes #16862.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
coq 8.4pl1

Closes #16861.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
jython 2.5.3

Closes #16859.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
svtplay-dl 0.8.2012.12.30

Closes #16809.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
mysql-related conflicts
sylpheed 3.3.0

Closes #16855.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
nrpe 2.14

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
poco 1.4.5

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
qpdf 4.0.0

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
swig 2.0.9

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
teem 1.11.0

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
xmlstarlet 1.4.2

Closes #16870.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
git-extras: remove duplicated caveats
postgresql conflicts with postgres-xc
cassandra 1.2.0

Closes #16868.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
superenv: make HOMEBREW_FILE available

Superenv scripts have a stripped PATH, which may not include
the brew binary itself. Make this explicitly available to
superenv scripts.

Fixes bsdmake wrapper.

Closes #16805.
Closes #16846.

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