posix: Move sys/stat.h to minimal libc

Newlib libc already provides sys/stat.h, so trying to have sys/stat.h
on the level of POSIX subsys inevitable leads to include order and
definition conflicts. Instead (as most of other sys/* includes)
should come from the underlying libc.

While moving, made unrelated change of removing #include <kernel.h>,
to accommodate the change reviewers.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>

lib/libc/minimal/include/sys/stat.h

@@ -1,9 +1,49 @@
 /*
- * Copyright (c) 2018 Linaro Limited
+ * Copyright (c) 2018 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#ifndef ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS_STAT_H_
+#define ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS_STAT_H_
 
-/* Dummy sys/stat.h to fulfill the requirements of certain libraries.
- */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define S_IRWXU 00700
+#define S_IRUSR 00400
+#define S_IWUSR 00200
+#define S_IXUSR 00100
+
+#define S_IRWXG 00070
+#define S_IRGRP 00040
+#define S_IWGRP 00020
+#define S_IXGRP 00010
+
+#define S_IRWXO 00007
+#define S_IROTH 00004
+#define S_IWOTH 00002
+#define S_IXOTH 00001
+
+/* File open modes */
+#define O_ACCMODE	   0003
+#define O_RDONLY	     00
+#define O_WRONLY	     01
+#define O_RDWR		     02
+
+#define SEEK_SET	0	/* Seek from beginning of file.  */
+#define SEEK_CUR	1	/* Seek from current position.  */
+#define SEEK_END	2	/* Seek from end of file.  */
+
+struct stat {
+	unsigned long st_size;
+	unsigned long st_blksize;
+	unsigned long st_blocks;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS_STAT_H_ */