Instead of having separate log functions for NuttX and POSIX, this now
switches everything to px4_log.h and PX4_INFO/WARN/ERR/DEBUG.
Also, the call mostly used is now a static inline function instead of a
macro which lead to a big increase in flash size for STM32.
The warnx and warn calls map to PX4_WARN.
Calls to errx or err genrtate a compile error.
The px4_log.h file implements a new log format:
For DEBUG and INFO:
<level> <msg>
For ERROR and WARN:
<level> <msg> (file filepath line linenum)
The verbosity can be changed by setting the macro to use
either linux_log or linux_log_verbose in px4_log.h
Signed-off-by: Mark Charlebois <charlebm@gmail.com>