RTPS and micro-CDR build system cleanup (#8084)

src/drivers/airspeed/airspeed.h

@@ -33,6 +33,7 @@
 
 #pragma once
 
+#include <string.h>
 #include <drivers/device/i2c.h>
 #include <drivers/drv_airspeed.h>
 #include <drivers/drv_hrt.h>

src/drivers/blinkm/blinkm.cpp

@@ -93,6 +93,8 @@
  *
  */
 
+#include <strings.h>
+
 #include <px4_config.h>
 
 #include <sys/types.h>