media-video/aegisub: version bump to 3.2.2

media-video/aegisub: version bump to 3.2.2

Inherited from Nikoli.
List of changes compared to Nikoli ebuilds:
- respect user compiler flags
- do not enable debug flags for regular builds
- omit unneeded ancient version numbers in deps
- unbundle luajit
- fix minor lua issues
- check for C++11 compiler support
- remove virtual/glu dep as it was only needed for crashreporter,
  which was never finished and ultimately was removed upstream
- avoid nls USE as build system expects config.rpath file being
  available regardless of the value of nls configure option

Gentoo-Bug: 536244
Gentoo-Bug: 508120