glsl: Add missing include guards

Signed-off-by: Michał Janiszewski <janisozaur+signed@gmail.com>

Reviewed-by: Brian Paul <brianp@vmware.com>

src/compiler/glsl/ir_builder.h

@@ -21,6 +21,9 @@
  * IN THE SOFTWARE.
  */
 
+#ifndef IR_BUILDER_H
+#define IR_BUILDER_H
+
 #include "ir.h"
 
 namespace ir_builder {
@@ -236,3 +239,5 @@ ir_if *if_tree(operand condition,
                ir_instruction *else_branch);
 
 } /* namespace ir_builder */
+
+#endif