GN: Override lsan and tsan suppression files.

BUG=webrtc:6236
NOTRY=True

Review-Url: https://codereview.webrtc.org/2274883002
Cr-Commit-Position: refs/heads/master@{#13897}
diff --git a/build_overrides/build.gni b/build_overrides/build.gni
index da8a1d5..576863e 100644
--- a/build_overrides/build.gni
+++ b/build_overrides/build.gni
@@ -19,3 +19,8 @@
 # Variable that can be used to support multiple build scenarios, like having
 # Chromium specific targets in a client project's GN file etc.
 build_with_chromium = false
+
+# Use our own suppressions files.
+asan_suppressions_file = "//build/sanitizers/asan_suppressions.cc"
+lsan_suppressions_file = "//webrtc/build/sanitizers/lsan_suppressions_webrtc.cc"
+tsan_suppressions_file = "//webrtc/build/sanitizers/tsan_suppressions_webrtc.cc"