Add missing header for Linux

src/platforms/posix/px4_layer/px4_posix_impl.cpp

@@ -49,6 +49,9 @@
 #include "hrt_work.h"
 #include <drivers/drv_hrt.h>
 #include "px4_time.h"
+#ifdef __PX4_LINUX
+#define _GNU_SOURCE
+#endif
 #include <pthread.h>
 
 extern pthread_t _shell_task_id;

src/platforms/posix/px4_layer/px4_posix_tasks.cpp

@@ -48,6 +48,10 @@
 #include <sched.h>
 #include <unistd.h>
 #include <string.h>
+#ifdef __PX4_LINUX
+#define _GNU_SOURCE
+#endif
+#include <pthread.h>
 
 #include <sys/stat.h>
 #include <sys/types.h>