POSIX and QuRT: fixed calls needing px4_ prefix

There were some missed calls to open and ioctl that need to be
px4_open and px4_ioctl.

QuRT also does not provide usleep() so px4_time.h has to be included
in files calling usleep.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/platforms/px4_debug.h

@@ -40,7 +40,11 @@
 
 #if defined(__PX4_LINUX) || defined(__PX4_QURT)
 
+#if defined(__PX4_LINUX)
 #include <err.h>
+#else
+#include <systemlib/err.h>
+#endif
 
 #define PX4_DBG(...)	
 #define PX4_INFO(...) 	warnx(__VA_ARGS__)