Forcing depth clear - not right, but gets atrain working.

src/xenia/gpu/gl4/command_processor.cc

@@ -2795,7 +2795,11 @@ bool CommandProcessor::IssueCopy() {
                  old_color_mask[2], old_color_mask[3]);
   }
 
-  if (depth_clear_enabled) {
+  // 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_clear_enabled) {
+  if (depth_target != kAnyTarget) {
     // Clear the current depth buffer.
     // TODO(benvanik): verify format.
     GLfloat depth = {(copy_depth_clear & 0xFFFFFF00) / float(0xFFFFFF00)};

src/xenia/gpu/gl4/gl4_shader_translator.cc

@@ -1366,7 +1366,7 @@ bool GL4ShaderTranslator::TranslateALU(const instr_alu_t* alu, int sync) {
         return false;
       }
     } else {
-      // assert_always();
+      assert_always();
       Append("  // <UNIMPLEMENTED>\n");
     }
   }