Fixes Fragment Shading Rate layered tests

Test was exporting Layer and ViewportIndex
decorations in Vertex Shader in the
Geometry Shader tests without checking
for support.

Components: Vulkan
VK-GL-CTS Issue: 2865

Affects:
dEQP-VK.fragment_shading_Rate.srlayered.*.gs
dEQP-VK.fragment_shading_Rate.colorlayered.*.gs

Change-Id: Idbf6be2c14bb8409feec2d7262efb9a402cf35a2
diff --git a/external/vulkancts/modules/vulkan/fragment_shading_rate/vktFragmentShadingRateBasic.cpp b/external/vulkancts/modules/vulkan/fragment_shading_rate/vktFragmentShadingRateBasic.cpp
index 290c505..47e916a 100644
--- a/external/vulkancts/modules/vulkan/fragment_shading_rate/vktFragmentShadingRateBasic.cpp
+++ b/external/vulkancts/modules/vulkan/fragment_shading_rate/vktFragmentShadingRateBasic.cpp
@@ -335,10 +335,13 @@
 		// Verify that we can read from the output variable
 		vss << "  if (gl_PrimitiveShadingRateEXT != pc.shadingRate) readbackok = 0;\n";
 
-		if (m_data.multiViewport)
-			vss << "  gl_ViewportIndex = instanceIndex & 1;\n";
-		if (m_data.colorLayered)
-			vss << "  gl_Layer = (instanceIndex & 2) >> 1;\n";
+		if (!m_data.geometryShader)
+		{
+			if (m_data.multiViewport)
+				vss << "  gl_ViewportIndex = instanceIndex & 1;\n";
+			if (m_data.colorLayered)
+				vss << "  gl_Layer = (instanceIndex & 2) >> 1;\n";
+		}
 	}
 
 	vss << "}\n";