wined3d: Simply use surface_modify_location() in IWineD3DSurfaceImpl_Map() with WINED3DLOCK_DISCARD.

The call to surface_add_dirty_rect() would have taken care of evicting the
other locations anyway, but we really shouldn't be touching the location flags
directly.

This fixes IBasicVideo:GetCurrentImage.

Accidentally made a worse leak by plugging a smaller one.

This will fix the hangs caused by trying to play audio/video files for
which the codecs are not enabled in gstreamer.

This reverts commit eb0e82a7.
It's causing different deadlocks, notably when a thread tries to
remove a handler inside a handler.

This should bring things to the mostly-regression-free-but-easier-to-debug
state I was expecting when I removed DIBs from many bitmaps.

comctl32/tests: Change expect_band_content test to ensure line numbers are reported correctly on test failure.