drivers epprom_simulator: Set standard source macro appropriately

This file uses several functions which are extensions to the the
std C library. Let's explicity select one of the extensions
which includes it instead of relaying on somebody having
set it for this file somewhere else.

(cherry picked from commit 1b94864)

Original-Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
GitOrigin-RevId: 1b94864
Change-Id: Ic66b060403b9dac5124fff98ea324aea96da3c74
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5242622
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Tristan Honscheid <honscheid@google.com>
Reviewed-by: Al Semjonovs <asemjonovs@google.com>
Tested-by: Tristan Honscheid <honscheid@google.com>
Tested-by: Al Semjonovs <asemjonovs@google.com>
Commit-Queue: Al Semjonovs <asemjonovs@google.com>

drivers/eeprom/eeprom_simulator.c

@@ -7,6 +7,20 @@
 
 #define DT_DRV_COMPAT zephyr_sim_eeprom
 
+#ifdef CONFIG_ARCH_POSIX
+#undef _POSIX_C_SOURCE
+/* Note: This is used only for interaction with the host C library, and is therefore exempt of
+ * coding guidelines rule A.4&5 which applies to the embedded code using embedded libraries
+ */
+#define _POSIX_C_SOURCE 200809L
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include "cmdline.h"
+#include "soc.h"
+#endif
+
 #include <zephyr/device.h>
 #include <zephyr/drivers/eeprom.h>
 
@@ -17,15 +31,6 @@
 #include <string.h>
 #include <errno.h>
 
-#ifdef CONFIG_ARCH_POSIX
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include "cmdline.h"
-#include "soc.h"
-#endif
-
 #define LOG_LEVEL CONFIG_EEPROM_LOG_LEVEL
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(eeprom_simulator);