Add `sigset64_t` and accompanying functions.

This doesn't address `struct sigaction` and `sigaction`. That will
come later.

Bug: http://b/72493232
Test: ran tests
Change-Id: I4134346757ce3a4dac6feae413361cec16223386
diff --git a/libc/bionic/sys_epoll.cpp b/libc/bionic/sys_epoll.cpp
new file mode 100644
index 0000000..9f82912
--- /dev/null
+++ b/libc/bionic/sys_epoll.cpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <sys/epoll.h>
+
+#include "private/SigSetConverter.h"
+
+extern "C" int __epoll_pwait(int, epoll_event*, int, int, const sigset64_t*, size_t);
+
+int epoll_create(int size) {
+  if (size <= 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  return epoll_create1(0);
+}
+
+int epoll_pwait(int fd, epoll_event* events, int max_events, int timeout, const sigset_t* ss) {
+  SigSetConverter set;
+  sigset64_t* ss_ptr = nullptr;
+  if (ss != nullptr) {
+    set = {};
+    set.sigset = *ss;
+    ss_ptr = &set.sigset64;
+  }
+  return epoll_pwait64(fd, events, max_events, timeout, ss_ptr);
+}
+
+int epoll_pwait64(int fd, epoll_event* events, int max_events, int timeout, const sigset64_t* ss) {
+  return __epoll_pwait(fd, events, max_events, timeout, ss, sizeof(*ss));
+}
+
+int epoll_wait(int fd, struct epoll_event* events, int max_events, int timeout) {
+  return epoll_pwait64(fd, events, max_events, timeout, nullptr);
+}