Fix GL4 alpha test, use blend disable flag

If color clear is enabled, grab the color target no matter what.
Update texture readback code on copy (but not enabled)
Track PA_SC_VIZ_QUERY in UpdateRasterizerState

src/xenia/gpu/gl4/gl4_command_processor.h

@@ -192,6 +192,7 @@ class GL4CommandProcessor : public CommandProcessor {
     uint32_t pa_sc_screen_scissor_tl;
     uint32_t pa_sc_screen_scissor_br;
     uint32_t multi_prim_ib_reset_index;
+    uint32_t pa_sc_viz_query;
     PrimitiveType prim_type;
 
     UpdateRasterizerStateRegisters() { Reset(); }