[meta-xilinx] tools: app.tcl exits 0 regardless of build failure

[Jean-Francois Dagenais]

> On Jun 2, 2017, at 16:03, Manjukumar Harthikote Matha <manjukumar.harthikote-matha at xilinx.com> wrote:
> 
> Yes we are aware of this issue, this will happen only if you have built the firmware successfully before. If it is a clean project it would fail during do_deploy mechanism.

This depends on a clean state, something that is not respectful of Yocto's normal behaviour. Plus it falsely fail at do_deploy, which is completely misleading.

In the short term, as Mike suggests, the compile step could start by removing the output from it's workdir, then test it's presence at the end. I will see about making a patch for this.