Added missing writes to gl_Position in vertex shaders

Some vertex shaders are not writing a value to gl_Position, which can cause
unintended run-time behavior (including termination or system instability).

Components: Vulkan
VK-GL-CTS issue: 1579

Affects:
dEQP-VK.binding_model.descriptorset_random.*
dEQP-VK.memory_model.message_passing.*

Change-Id: I3f2f21f23508bda3062a4480e9fac78748bab32b

external/vulkancts/modules/vulkan/binding_model/vktBindingDescriptorSetRandomTests.cpp

@@ -700,6 +700,7 @@ void DescriptorSetRandomTestCase::initPrograms (SourceCollections& programCollec
 				"  uvec4 color = (accum != 0) ? uvec4(0,0,0,0) : uvec4(1,0,0,1);\n"
 				"  imageStore(image0_0, ivec2(gl_VertexIndex % " << DIM << ", gl_VertexIndex / " << DIM << "), color);\n"
 				"  gl_PointSize = 1.0f;\n"
+				"  gl_Position = vec4(0.0f, 0.0f, 0.0f, 1.0f);\n"
 				"}\n";
 
 			programCollection.glslSources.add("test") << glu::VertexSource(vss.str());

external/vulkancts/modules/vulkan/memory_model/vktMemoryModelMessagePassing.cpp

@@ -406,8 +406,9 @@ void MemoryModelTestCase::initPrograms (SourceCollections& programCollection) co
 			"   uint bufferCoord        = gl_VertexIndex;\n"
 			"   uint partnerBufferCoord = subgroupShuffleXor(gl_VertexIndex, gl_SubgroupSize-1);\n"
 			"   ivec2 imageCoord        = ivec2(gl_VertexIndex % (DIM*NUM_WORKGROUP_EACH_DIM), gl_VertexIndex / (DIM*NUM_WORKGROUP_EACH_DIM));\n"
-			"   ivec2 partnerImageCoord = subgroupShuffleXor(imageCoord, gl_SubgroupSize-1);\n\n"
-			"   gl_PointSize			= 1.0f;\n\n";
+			"   ivec2 partnerImageCoord = subgroupShuffleXor(imageCoord, gl_SubgroupSize-1);\n"
+			"   gl_PointSize            = 1.0f;\n"
+			"   gl_Position             = vec4(0.0f, 0.0f, 0.0f, 1.0f);\n\n";
 			break;
 		case STAGE_FRAGMENT:
 			css <<
@@ -456,8 +457,9 @@ void MemoryModelTestCase::initPrograms (SourceCollections& programCollection) co
 			"   uint bufferCoord        = globalId.y * DIM*NUM_WORKGROUP_EACH_DIM + globalId.x;\n"
 			"   uint partnerBufferCoord = partnerGlobalId.y * DIM*NUM_WORKGROUP_EACH_DIM + partnerGlobalId.x;\n"
 			"   ivec2 imageCoord        = globalId;\n"
-			"   ivec2 partnerImageCoord = partnerGlobalId;\n\n"
-			"   gl_PointSize			= 1.0f;\n\n";
+			"   ivec2 partnerImageCoord = partnerGlobalId;\n"
+			"   gl_PointSize            = 1.0f;\n"
+			"   gl_Position             = vec4(0.0f, 0.0f, 0.0f, 1.0f);\n\n";
 			break;
 		case STAGE_FRAGMENT:
 			css <<