Move uio enums to sys/_uio.h.

Include _uio.h instead of uio.h in several headers to reduce header
polution.

Fix a few places that relied on header polution to get the uio.h header.

I have not moved struct uio as many more things that use it rely on
header polution to get other definitions from uio.h.

Reviewed by:	cem, kib, markj
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D14811

newlib/libc/sys/rtems/include/sys/_uio.h

@@ -0,0 +1,52 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1982, 1986, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *	@(#)uio.h	8.5 (Berkeley) 2/22/94
+ * $FreeBSD$
+ */
+
+#ifndef _SYS__UIO_H_
+#define	_SYS__UIO_H_
+
+#if __BSD_VISIBLE
+enum uio_rw {
+	UIO_READ,
+	UIO_WRITE
+};
+
+/* Segment flag values. */
+enum uio_seg {
+	UIO_USERSPACE,		/* from user data space */
+	UIO_SYSSPACE,		/* from system space */
+	UIO_NOCOPY		/* don't copy, already in object */
+};
+#endif /* __BSD_VISIBLE */
+
+#endif /* !_SYS__UIO_H_ */

newlib/libc/sys/rtems/include/sys/uio.h

@@ -38,6 +38,7 @@
 #include <sys/cdefs.h>
 #include <sys/_types.h>
 #include <sys/_iovec.h>
+#include <sys/_uio.h>
 
 #ifndef _SSIZE_T_DECLARED
 typedef	__ssize_t	ssize_t;
@@ -49,17 +50,6 @@ typedef	__off_t	off_t;
 #define	_OFF_T_DECLARED
 #endif
 
-#if __BSD_VISIBLE
-enum	uio_rw { UIO_READ, UIO_WRITE };
-
-/* Segment flag values. */
-enum uio_seg {
-	UIO_USERSPACE,		/* from user data space */
-	UIO_SYSSPACE,		/* from system space */
-	UIO_NOCOPY		/* don't copy, already in object */
-};
-#endif
-
 #ifdef _KERNEL
 
 struct uio {