epoll_create1: fix flags decoding

* xlat/epollflags.in: Remove EPOLL_NONBLOCK, provide fallback definition
for EPOLL_CLOEXEC.
* tests/epoll_create1.c: New file.
* tests/epoll_create1.expected: Likewise.
* tests/epoll_create1.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add epoll_create1.
(TESTS): Add epoll_create1.test.
(EXTRA_DIST): Add epoll_create1.expected.
* tests/.gitignore: Add epoll_create1.
diff --git a/tests/.gitignore b/tests/.gitignore
index 9b73a95..ee71e78 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -1,5 +1,6 @@
 bpf
 caps
+epoll_create1
 eventfd
 execve
 execveat