Remove stale AlsaWrapper TSan suppression

Per the bug, there were two issues, one of which was fixed and the other
sounds like it was fixed in newer ALSA in 2014 (comment #17). Remove the
suppression.

Bug: 374135
Change-Id: I37c8ca04dd9c7cf8d33b12940cd5457b0cbe6e5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1641202Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Auto-Submit: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665590}

build/sanitizers/tsan_suppressions.cc

@@ -128,9 +128,6 @@ char kTSanDefaultSuppressions[] =
     "race:sctp_express_handle_sack\n"
     "race:system_base_info\n"
 
-    // http://crbug.com/374135
-    "race:media::AlsaWrapper::PcmWritei\n"
-
     // False positive in libc's tzset_internal, http://crbug.com/379738.
     "race:tzset_internal\n"