Previous we disabled some plugins that we want to keep around but can't port
yet by setting `build_by_default` to `false`. However, this isn't working on
many machines. I haven't figured out why, so instead lets just make their
meson.build files exit early.
Testing Done:
Ran the turtles on a machine that was still building these plugins.
Reviewed at https://reviews.imfreedom.org/r/3142/
# UPDATING VERSION NUMBERS FOR RELEASES
#
# The version number is:
# <major>.<minor>.<micro><extra>
#
# micro += 1
#
# If any functions have been added to libpurple or Pidgin:
# micro = 0
# minor += 1
#
# If backwards compatibility has been broken in libpurple or Pidgin:
# micro = 0
# minor = 0
# major += 1
# purple_soversion += 1
#
# extra should be similar to one of the following: