Reverting depth clear restriction in #330.

The comment is still true: games seem to need more clears.

src/xenia/gpu/gl4/gl4_command_processor.cc

@@ -1872,8 +1872,7 @@ bool GL4CommandProcessor::IssueCopy() {
   // TODO(benvanik): figure out real condition here (maybe when color cleared?)
   // HACK: things seem to need their depth buffer cleared a lot more
   // than as indicated by the depth_clear_enabled flag.
-  // if (depth_target != kAnyTarget) {
-  if (depth_clear_enabled && depth_target != kAnyTarget) {
+  if (depth_target != kAnyTarget) {
     // Clear the current depth buffer.
     // TODO(benvanik): verify format.
     GLfloat depth = {(copy_depth_clear & 0xFFFFFF00) /