Add functions to interact with ASan and MSan, and some sample uses

The sample uses are from when I debugged bug 617124. The change in neteq_network_stats_unittest.cc is a fix for a minor unrelated bug found by the try bots when I tried to land this CL (a test was passing uninitialized packet data to NetEq).

BUG=chromium:617124

Review-Url: https://codereview.webrtc.org/2293893002
Cr-Commit-Position: refs/heads/master@{#14034}

webrtc/modules/audio_coding/codecs/ilbc/create_augmented_vec.c

@@ -18,6 +18,7 @@
 
 #include "defines.h"
 #include "constants.h"
+#include "webrtc/base/sanitizer.h"
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
 
 /*----------------------------------------------------------------*
@@ -40,6 +41,9 @@ void WebRtcIlbcfix_CreateAugmentedVec(
    */
   size_t interp_len = WEBRTC_SPL_MIN(index, 4);
 
+  rtc_MsanCheckInitialized(buffer - index - interp_len, sizeof(buffer[0]),
+                           index + interp_len);
+
   ilow = index - interp_len;
 
   /* copy the first noninterpolated part */