Add winmm.lib as a Windows dep for timeutils.

timeutils.cc uses timeGetTime, which is from winmm.

Bug: None
Change-Id: I8e40f1c01c1128a80e9b5c59c0b28d39b3d0893a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128521
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27172}

rtc_base/BUILD.gn

@@ -410,6 +410,10 @@ rtc_source_set("timeutils") {
     ":safe_conversions",
     ":stringutils",
   ]
+  libs = []
+  if (is_win) {
+    libs += [ "winmm.lib" ]
+  }
 }
 
 rtc_source_set("stringutils") {