Add support for std140 qualifier (#1153)

Updates the AST builder and adds a class for the qualifier.

Author: AaronGhost

ast/src/main/java/com/graphicsfuzz/common/ast/type/Std140LayoutQualifier.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2021 The GraphicsFuzz Project Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.graphicsfuzz.common.ast.type;
+
+public class Std140LayoutQualifier implements LayoutQualifier {
+
+  @Override
+  public String toString() {
+    return "std140";
+  }
+
+}

ast/src/main/java/com/graphicsfuzz/common/ast/visitors/AstBuilder.java

@@ -78,6 +78,7 @@
 import com.graphicsfuzz.common.ast.type.QualifiedType;
 import com.graphicsfuzz.common.ast.type.SamplerType;
 import com.graphicsfuzz.common.ast.type.SetLayoutQualifier;
+import com.graphicsfuzz.common.ast.type.Std140LayoutQualifier;
 import com.graphicsfuzz.common.ast.type.Std430LayoutQualifier;
 import com.graphicsfuzz.common.ast.type.StructDefinitionType;
 import com.graphicsfuzz.common.ast.type.StructNameType;
@@ -1664,6 +1665,8 @@ private LayoutQualifier processLayoutQualifierId(
       switch (layoutQualifierId.IDENTIFIER().getText()) {
         case "std430":
           return new Std430LayoutQualifier();
+        case "std140":
+          return new Std140LayoutQualifier();
         default:
           return new UnknownLayoutQualifier(layoutQualifierId.getText());
       }