This includes support for statically linked plugins. It vastly increases
the test iteration speed, which is critical for fuzz testing.
Furthermore, it is necessary for coverage-driven fuzz testing to work at
all.

This also provides a (manually compiled only) back-end for LLVM's
LibFuzzer using mostly the same code.

1) Debugging, regression testing or unguided fuzzing:
  - Make a normal build (debug and sanitization recommended).
  - Execute: "test/vlc-demux-run [demux name] <file path>"

2) American Fuzzy Lop run:
  - Make a *static* build with AFL as the toolchain.
  - (Where applicable) perform adequate religious luck granting
    offerings or other rites.
  - Run AFL with test/vlc-demux-run as the fuzzed executable.

3) LibFuzzer:
  - Make a preferrably static build with Clang as the toolchain.
  - Manually build test/vlc-demux-libfuzzer.
  - Run the executable with the LibFuzzer command line parameters syntax.