Most of the incompatitbilities are luckily similar to the darwin build.
- New target OS __PX4_CYGWIN added because in other build environments on Windows defines will very likely be completely different
- added all necessary exeptions to the defines
- disabled priorities completely because on Windows they are defined 1-32 and with all the arbitrary +40 -40 priority settings there were a lot of problems
  not only did some threads/"virtual tasks" not start because of out of bound priorities but also the resulting scheduling was totally random and inadequate
  with default priorities it ran toally fine during my first tests, should be rethought when windows is used onboard in the future

* Fix several valgrind identified mem leaks

* Added callgrind target.

* px4_posix_tasks use nullptr

The thread name is used from within the entry of the new thread, but the
provided name could live on the stack of the caller thread. Thus we need to
copy the name.

this makes it consistent with other functions, like px4_task_spawn_cmd()
and px4_task_kill()

When running a simulation with, for example,
make posix jmavsim
px4 crashed almost 100% reproducable near start up.

This turned out to be a stack overflow. On gitter
it was suggested that the main reason for this could
be stack sizes, as currently used, assume a 32bit pointer
size and that doubling the stack size for everything
but NuttX would be the Right Thing.

This is the solution that I came up with (it makes
my core dumps disappear).

- __BEGIN_DECLS is for declarations not definitions
- getprogname() declaration is in err.h

The stack size cannot be less than PTHREAD_STACK_MIN.

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

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

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

POSIX: Improve shell so it does not spam the user, enable CTRL-C to actually quit the application. Twiddle the app boot delay to avoid a race with the commander app. Needs a proper fix on the startup sequencing.

In order to use upstart to run PX4 it needs to run in daemon mode.
Added ability to test if a task is running in order to gracefully
shut down muorb.

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

Ifdefed out deadcode in position_estimator_inav_main.c as the
deadcode does not compile for qurt.

Added fixes to get a successful build for posix-arm and qurt targets.
Removed CLOCK_REALTIME def from px4_time.h for qurt and removed unused
variables in att_est_q and mc_att_control.

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