Improving APM fuzzer coverage.
Improving APM fuzzer coverage.

Reading the fuzzer coverage report for audio_processing_fuzzer, I
noticed that AgcManagerDirect::AnalyzePreProcess was never
called. That turned out to be because GainControl was never
enabled. This change optionally calls 'Enable' on GainControl and 6
other public submodules of the APM.

Bug: webrtc:7820
Change-Id: Iae9da16f9f14fe7d3cd3318836d0d6e131a7ac39
Reviewed-on: https://webrtc-review.googlesource.com/12924
Reviewed-by: Henrik Lundin <b9599afb29b1fa4305dba8bb04f760bf0c9c9471@webrtc.org>
Commit-Queue: Alex Loiko <999d0b481e5703ad7006f0848e249f8b2c3f29bd@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#20334}
TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc