posix: struct timespec: Move definition to sys/_timespec.h

POSIX subsys defines struct timespec in <time.h> (as POSIX public
API requires), but newlib defines in in sys/_timespec.h, which
inevitably leads to inclusion order and redifinition conflicts.
Follow newlib way and define it in single place, sys/_timespec.h,
which belongs to libc namespace. Thus, we move current definition
to minimal libc, and will use either minlibc's or newlib's
definition, instead of trying to redefine it.

This is similar to the introduction of sys/_timeval.h done earlier.

Signed-off-by: Paul Sokolovsky <[email protected]>

Author: pfalcon

include/posix/time.h

@@ -10,14 +10,7 @@
 extern "C" {
 #endif
 
-
-#ifndef __timespec_defined
-#define __timespec_defined
-struct timespec {
-	signed int tv_sec;
-	signed int tv_nsec;
-};
-#endif
+#include <sys/_timespec.h>
 
 /* Older newlib's like 2.{0-2}.0 don't define any newlib version defines, only
  * __NEWLIB_H__ so we use that to decide if itimerspec was defined in

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

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2019 Linaro Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS__TIMESPEC_H_
+#define ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS__TIMESPEC_H_
+
+#include <sys/types.h>
+
+struct timespec {
+	time_t tv_sec;
+	long tv_nsec;
+};
+
+#endif /* ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS__TIMESPEC_H_ */