tests: add epoll_ctl.test

* tests/epoll_ctl.c: New file.
* tests/epoll_ctl.test: New test.
* tests/.gitignore: Add epoll_ctl.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add epoll_ctl.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index 0478e18..849d6ef 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -27,6 +27,7 @@
 dup3
 epoll_create
 epoll_create1
+epoll_ctl
 eventfd
 execve
 execve-v