[PATCH 0/1] MR1884: d3d8: Filter out redundant buffer discards.

[Zebediah Figura (＠zfigura)]

I was unable to write tests for this; it seems it doesn't consistently work on
Windows. However, Rayman 3 seems to rely on it; it maps the same buffer twice
immediately after creation, with DISCARD flags on both maps, and expects the
same address to be returned.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53752