zink: emulated alpha formats do not require mutable

cc: mesa-stable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35433>

src/gallium/drivers/zink/ci/zink-anv-adl-fails.txt

@@ -669,7 +669,6 @@ dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_revers
 dEQP-GLES3.functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_dst_x,Fail
 spec@ext_framebuffer_multisample@interpolation 6 non-centroid-deriv-disabled,Fail
 
-glx@glx-tfp,Fail
 spec@arb_sample_shading@samplemask 4,Fail
 spec@ext_framebuffer_multisample@interpolation 6 centroid-deriv-disabled,Fail
 spec@ext_framebuffer_multisample@interpolation 8 non-centroid-deriv-disabled,Fail

src/gallium/drivers/zink/zink_format.h

@@ -58,6 +58,9 @@ zink_format_needs_mutable(enum pipe_format a, enum pipe_format b)
       return util_format_linear(a) != b;
    if (util_format_is_srgb(b))
       return util_format_linear(b) != a;
+   if (zink_format_emulate_x8(b) == a || zink_format_emulate_x8(a) == b ||
+       zink_format_get_emulated_alpha(b) == a || zink_format_get_emulated_alpha(a) == b)
+      return false;
    return true;
 }
 #endif