loongarch: Add loongarch architecture support.

Copied from chromium's build/build_config.h

No-Try: True
Bug: webrtc:14433
Change-Id: I5ab4dbb49bd74aa8f6f6054776d9f1f3d606d914
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275288
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Andrey Logvin <landrey@google.com>
Cr-Commit-Position: refs/heads/main@{#38067}
diff --git a/AUTHORS b/AUTHORS
index ebcdd21..2fdd9fd 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -172,6 +172,7 @@
 Videxio AS <*@videxio.com>
 Vidyo, Inc. <*@vidyo.com>
 Vonage Holdings Corp. <*@vonage.com>
+Wang Qing <wangqing-hf@loongson.cn>
 Wire Swiss GmbH <*@wire.com>
 &yet LLC <*@andyet.com>
 # END organizations section.