meson: directories missing meson.build files

Submitted by Olivier Crête @ocrete

Link to original bug (#784134)

Description

Generated using:
 diff <(find . -name Makefile.am | xargs -n1 dirname) <(find . -name meson.build | xargs -n1 dirname) |grep '^<'

< ./docs/plugins
< ./tests/icles
< ./tests/examples/equalizer
< ./tests/examples/jack
< ./tests/examples
< ./tests/examples/spectrum
< ./tests/examples/cairo
< ./tests/examples/v4l2
< ./tests/examples/shapewipe
< ./tests/examples/rtp
< ./tests/examples/audiofx
< ./tests/examples/level
< ./tests/files

< ./ext/libcaca
< ./ext/aalib
< ./ext/raw1394

< ./sys/sunaudio
< ./sys/oss4
< ./sys/osxaudio
< ./sys/waveform
< ./sys/osxvideo
< ./sys/oss