Write gl_PointSize in depth tests

Some depth tests use VK_PRIMITIVE_TOPOLOGY_POINT_LIST but the shaders
don't write the point size

Components: Vulkan

VK-GL-CTS issue: 4153

Affected tests:
dEQP-VK.pipeline.*.depth.*

Change-Id: Idaa9ea65f7c43ca02d7780d1825d4558b712a133
diff --git a/external/vulkancts/modules/vulkan/pipeline/vktPipelineDepthTests.cpp b/external/vulkancts/modules/vulkan/pipeline/vktPipelineDepthTests.cpp
index c715290..112bbb7 100644
--- a/external/vulkancts/modules/vulkan/pipeline/vktPipelineDepthTests.cpp
+++ b/external/vulkancts/modules/vulkan/pipeline/vktPipelineDepthTests.cpp
@@ -286,6 +286,7 @@
 			"void main (void)\n"
 			"{\n"
 			"	gl_Position = position;\n"
+			"	gl_PointSize = 1.0f;\n"
 			"}\n");
 	}