Meta: Add pre-push hook to repo

This doesn't cause it to be run, of course, but it can be symlinked
into place by the user.  Better to commit it than to lose it by
accident sometime.

hooks/pre-push

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+# * Commit parameters
+# Unused now, but good for future reference.  See man 5 githooks.
+
+remote="$1"
+url="$2"
+
+read local_ref local_sha remote_ref remote_sha
+
+# * Run tests
+
+# Not using sandbox and auto-install, because "git push" shouldn't
+# cause remote code to be downloaded and executed (i.e. what would
+# happen by installing packages).  It can be done manually when needed.
+
+make test