Add a couple of CG_TRACEs

Change-Id: If1f3f4aafd6fde4fcf916b31e7447667baa1bfd0
I think we should begin a new path in drawPolyLine()

Change-Id: I113ab237561ae83a2d256be7ff14bea6432f0d06
Don't bother logging the CGContextSetLineWidth() here either

Change-Id: I95860cd9edec474b656a7f4cc2847ef48868d699
Fill these buffers, too, with easily recognizable junk in dbgutil mode

Change-Id: I7ad8ae6b4995b45deea18270348f6ce626aa1ed6
Log correct depth for the created CGBitmapContext

Change-Id: Icbcc4027d3fd9cb195c5fc6fd50f1ffaa7ce0d28
Add somewhat ridiculous debug hacks for CoreGrahics drawing debugging on iOS

When the environment variable DRAW_INCREMENTALLY_FROM is set to a
number, we want TiledLibreOffice to loop, initially performing only
that number of drawing operations in AquaSalGraphics, then wait for
some seconds, and redraw. Next time perform one operation
more. Repeat.

Implemented in vcl by surrounding the entry and exit(s) of the drawing
functions in AquaSalGraphics with macros.

All this is active only for iOS and in a dbgutil build.