pyqt 4.10.4

Closes #27826.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
Check existence of target keg instead of hiding exceptions
L-SMASH 1.5.0
x264: improve the formula and update to r2397
x264: add r2397 bottle.
l-smash: add 1.5.0 bottle.