pager: drop unused global vars

We use global when we need to write to a variable, not read it.
This function only reads, so drop the keyword.

Change-Id: Iee91998fba67fd3e8ebaf2f4a79f95032f70b1c0
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/464501
Reviewed-by: Scott Lee <ddoman@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>

pager.py

@@ -40,7 +40,7 @@ def RunPager(globalConfig):
 
 
 def TerminatePager():
-    global pager_process, old_stdout, old_stderr
+    global pager_process
     if pager_process:
         sys.stdout.flush()
         sys.stderr.flush()