Vulkan: enable the rest of dEQP tests in fbo.render.*

Vulkan does not support separate depth and stencil attachments.
Adding this check to checkStatus skips the relevant tests to that.

There was also a bug in FramebufferVk::clear where we were not
checking the number of bits for depth/stencil attachments before
setting the aspects for clearing.

Bug: angleproject:2597
Change-Id: Iabe9f77a51fc7aca08b8faf3cecc3df9f99a7f1e
Reviewed-on: https://chromium-review.googlesource.com/1107847
Commit-Queue: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
index 53274ae..222e4c3 100644
--- a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
+++ b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
@@ -293,8 +293,7 @@
 {
     // if we have both a depth and stencil buffer, they must refer to the same object
     // since we only support packed_depth_stencil and not separate depth and stencil
-    if (mState.getDepthAttachment() != nullptr && mState.getStencilAttachment() != nullptr &&
-        mState.getDepthStencilAttachment() == nullptr)
+    if (mState.hasSeparateDepthAndStencilAttachments())
     {
         return false;
     }