SPV 1.4: Add testing infrastructure for SPV 1.4 tests.

This includes the test for the first feature of OpEntryPoint.

Test/spv.1.4.OpEntryPoint.frag

@@ -0,0 +1,27 @@
+#version 450
+
+layout(location = 0) in vec4 inv;
+layout(location = 0) out vec4 outv;
+
+vec4 globalv;
+
+layout(binding = 0) uniform ubt {
+    vec4 v;
+} uniformv;
+
+layout(binding = 1) buffer bbt {
+    float f;
+} bufferv;
+
+layout(binding = 2, push_constant) uniform pushB {
+    int a;
+} pushv;
+
+void main()
+{
+    vec4 functionv;
+    functionv = inv;
+    globalv = inv;
+    outv = functionv + inv + globalv + uniformv.v * pushv.a * bufferv.f;
+    outv += functionv + inv + globalv + uniformv.v * pushv.a * bufferv.f;
+}