To prevent too much disruption to people who have our public projects as
part of their build or testing systems we are temporarily ignoring a
warning about using Xcode 15.

Xcode 14 has minimum deployment targets of macos 10.13 and iOS 11.

This restores the functionality of JUCE_COREGRAPHICS_RENDER_WITH_MULTIPLE_PAINT_CALLS.
Using this preprocessor flag may avoid Core Graphics rendering much larger regions than
necessary, but the small regions that are rendered will likely be rendered slower.
Whether using this flag improves or degrades the performance of your rendering overall
will be specific to each application.

Previously enabling JUCE_COREGRAPHICS_RENDER_WITH_MULTIPLE_PAINT_CALLS was ineffective
from versions of macOS around 10.13, but enabling it didn't have any negative impact on
performance. Now enabling JUCE_COREGRAPHICS_RENDER_WITH_MULTIPLE_PAINT_CALLS may result
in slower rendering.