pre-upload.py: run basic source checks on .{policy,conf} files

Add a few other types of text files to the common file extensions to
check for basic issues, like old license headers.

BUG=none
TEST=run presubmit checks on my seccomp policies with old license text
TEST=`./pre-upload_unittest.py` passes

Change-Id: I3456962d93374d31985d1ec951a2147c8168d308
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/353163
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 36d31ff..2c14bb5 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -50,6 +50,7 @@
     r"(^|.*[\\\/])[^.]+$",
     # Other
     r".*\.java$", r".*\.mk$", r".*\.am$",
+    r".*\.policy$", r".*\.conf$",
 ]