memcheck: need AP_HAL_Boards import for CONFIG_HAL_BOARD configs to make sense

* with great programming in c preprocessor comes great responsibility

libraries/memcheck/memcheck.cpp

@@ -7,6 +7,7 @@
 
 #include <stdlib.h>
 #include <stdint.h>
+#include <AP_HAL_Boards.h>
 
 static const uint32_t *stack_low;
 extern unsigned __brkval;