unity launches blender in background mode to do some
file conversions, ever since the launcher got introduced
this process broke.
The root cause here is: Unity looks up the default program
to launch .blend files with, which is now the launcher, then
launches it in background mode with a script to export the data.
The launcher however was designed to exit as quickly as
possible so there would not be an extra background process
lingering. It does not wait for blender to exit and does not
pass back any error codes.
This broke unity's workflow since it assumed if the process
exits and succeeds the data *must* be ready for reading which
no longer holds true.
This change keeps the launcher design as was previously,
*except* when launching in background mode, then it
waits and passes back any error codes, thus restoring
unity's workflow.
Differential Revision: https://developer.blender.org/D13894
Reviewed by: LazyDodo, Brecht
blender-laucher.c was not an ideal name for this file
since it's not directly clear it is windows only.
This change renames it to blender_launcher_win32.c
to be more in line with other win32 specific files
we have.
