Use multiple globs/emails in per-file syntax

Bug: 112259427
Test: tools/checkowners.py -c -v OWNERS */OWNERS */*/OWNERS
Change-Id: I0e2c2c64a23df360fbe7691c4336ca04099fba13
diff --git a/OWNERS b/OWNERS
index 1e9b763..b9fee4e 100644
--- a/OWNERS
+++ b/OWNERS
@@ -2,10 +2,7 @@
 dwillemsen@google.com
 nanzhang@google.com
 
-per-file * = ccross@android.com
-per-file * = dwillemsen@google.com
-per-file * = nanzhang@google.com
+per-file * = ccross@android.com,dwillemsen@google.com,nanzhang@google.com
 
 # for version updates
-per-file version_defaults.mk = aseaton@google.com
-per-file version_defaults.mk = elisapascual@google.com
+per-file version_defaults.mk = aseaton@google.com,elisapascual@google.com