Add several simple if-statement tests

tests/if-01.glsl

@@ -0,0 +1,11 @@
+/* FAIL - if-statement condition is not bool scalar */
+
+uniform bvec4 a;
+
+void main()
+{
+  if (a)
+    gl_Position = vec4(1.0, 0.0, 0.0, 1.0);
+  else
+    gl_Position = vec4(0.0, 1.0, 0.0, 1.0);
+}

tests/if-02.glsl

@@ -0,0 +1,11 @@
+/* FAIL - if-statement condition is not bool scalar */
+
+uniform float a;
+
+void main()
+{
+  if (a)
+    gl_Position = vec4(1.0, 0.0, 0.0, 1.0);
+  else
+    gl_Position = vec4(0.0, 1.0, 0.0, 1.0);
+}

tests/if-03.glsl

@@ -0,0 +1,11 @@
+/* PASS */
+
+uniform bool a;
+
+void main()
+{
+  if (a)
+    gl_Position = vec4(1.0, 0.0, 0.0, 1.0);
+  else
+    gl_Position = vec4(0.0, 1.0, 0.0, 1.0);
+}

tests/if-04.glsl

@@ -0,0 +1,11 @@
+/* PASS */
+
+uniform bvec4 a;
+
+void main()
+{
+  if (a.x)
+    gl_Position = vec4(1.0, 0.0, 0.0, 1.0);
+  else
+    gl_Position = vec4(0.0, 1.0, 0.0, 1.0);
+}