[portability] Support unknown operating systems in gclient.

Detect the name of unknown operating systems using uname, if available,
since it doesn't append the operating system version.

Change-Id: Idab7bd0db65a8d424ec2fd48f06247405b6649e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4169240
Auto-Submit: Jonas Termansen <sortie@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
diff --git a/metrics.py b/metrics.py
index c5b86b6..11e43c6 100644
--- a/metrics.py
+++ b/metrics.py
@@ -241,7 +241,7 @@
     # Add metrics regarding environment information.
     self.add('timestamp', int(time.time()))
     self.add('python_version', metrics_utils.get_python_version())
-    self.add('host_os', gclient_utils.GetMacWinAixOrLinux())
+    self.add('host_os', gclient_utils.GetOperatingSystem())
     self.add('host_arch', detect_host_arch.HostArch())
 
     depot_tools_age = metrics_utils.get_repo_timestamp(DEPOT_TOOLS)