tests: add poll.test

* tests/poll.c: New file.
* tests/poll.test: New test.
* tests/.gitignore: Add poll.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(TESTS): Add poll.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index 1cee1f8..5671978 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -72,6 +72,7 @@
 pc
 personality
 pipe
+poll
 ppoll
 pselect6
 readdir