add cstring include need for strncmp

Propose resolution of Issue 10011 : (GCC) build fails desktop_capturer.cc:66:66: error: ‘strncmp’ was not declared in this scope

Bug: webrtc:10011
Change-Id: I4afdfd96f8bbc8e39380a365138ab79e237568e3
Reviewed-on: https://webrtc-review.googlesource.com/c/111885
Commit-Queue: Brave Yao <braveyao@webrtc.org>
Reviewed-by: Brave Yao <braveyao@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25790}
diff --git a/AUTHORS b/AUTHORS
index 16ae916..1216b48 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -76,6 +76,7 @@
 Tomas Popela <tomas.popela@gmail.com>
 Jan Grulich <grulja@gmail.com>
 Eike Rathke <erathke@redhat.com>
+Michel Promonet <michel.promonet.1@gmail.com>
 
 &yet LLC <*@andyet.com>
 Agora IO <*@agora.io>