Attempt to reland: Allow intelligibility to compile in apm (https://codereview.webrtc.org/1182323005/)

Revert of original: https://codereview.webrtc.org/1187033005/

Changes in original:
- Added files to gyp and BUILD
- Made minor fixes to get everything to compile
    and intelligibility_proc to run
- Added comments
- Auto-reformatting

New Changes:
- Added <numeric> header to intelligibility_enhancer.cc to address buildbot errors
- Switched to use WAV for i/o in intelligibility_proc.cc to address windows errors
- clean up

Note: Patch 1 duplicates Patch 7 of https://codereview.webrtc.org/1182323005/

R=andrew@webrtc.org

Review URL: https://codereview.webrtc.org/1190733004.

Cr-Commit-Position: refs/heads/master@{#9486}

webrtc/modules/audio_processing/audio_processing_tests.gypi

@@ -59,6 +59,20 @@
         'beamformer/nonlinear_beamformer_test.cc',
       ],
     }, # nonlinear_beamformer_test
+    {
+      'target_name': 'intelligibility_proc',
+      'type': 'executable',
+      'dependencies': [
+        'audioproc_test_utils',
+        '<(DEPTH)/third_party/gflags/gflags.gyp:gflags',
+        '<(DEPTH)/testing/gtest.gyp:gtest',
+        '<(webrtc_root)/modules/modules.gyp:audio_processing',
+        '<(webrtc_root)/test/test.gyp:test_support',
+      ],
+      'sources': [
+        'intelligibility/intelligibility_proc.cc',
+      ],
+    }, # intelligibility_proc
   ],
   'conditions': [
     ['enable_protobuf==1', {