Fix warnings like this:
<command-line>:0:21: warning: "APM_BUILD_DataFlash_test" is not defined [-Wundef]
/home/lucas/p/dronecode/ardupilot/libraries/AP_Vehicle/AP_Vehicle_Type.h:36:41: note: in expansion of macro ‘APM_BUILD_DIRECTORY’
#define APM_BUILD_TYPE(type) ((type) == APM_BUILD_DIRECTORY)
^
These happen because we are trying to set APM_BUILD_DIRECTORY to undefined
values. We should rather default to the APM_BUILD_DIRECTORY ==
APM_BUILD_UNKNOWN
2c029ae1f9