Fix 3D blit's z-clamp

Z was compared against height instead of depth.

Bug: angleproject:419755713
Change-Id: Ie17a1672e8f3006ec72c1eee9a315832c8d1976a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/75548
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Geoff Lang <geofflang@google.com>
Commit-Queue: Geoff Lang <geofflang@google.com>
Reviewed-by: Geoff Lang <geofflang@google.com>

src/Device/Blitter.cpp

diff --git a/src/Device/Blitter.cpp b/src/Device/Blitter.cpp
index c42448d..76addb3 100644
--- a/src/Device/Blitter.cpp
+++ b/src/Device/Blitter.cpp
@@ -1573,7 +1573,7 @@
 		if(state.filter3D)
 		{
 			Int Z1 = Z0 + 1;
-			Z1 = IfThenElse(Z1 >= sHeight, Z0, Z1);
+			Z1 = IfThenElse(Z1 >= sDepth, Z0, Z1);
 
 			Pointer<Byte> s000 = source + ComputeOffset(X0, Y0, Z0, sSliceB, sPitchB, srcBytes);
 			Pointer<Byte> s010 = source + ComputeOffset(X1, Y0, Z0, sSliceB, sPitchB, srcBytes);