Nominally renamed the AquaSalGraphics class to QuartzSalGraphics, as
it isn't now then "Aqua" (Mac OS X) specific any more.

Actually, for Mac OS X, because lots of code in vcl/aqua expects it to
be called AquaSalGraphics (just like the alternative class used when
using the obsolete ATSUI API on Mac OS X), use a #define to make it
still be called AquaSalGraphics to the compiler's eyes. For iOS it can
be called QuartzSalGraphics.