glsl: Make some files safe to include from C

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/ir.h

@@ -36,6 +36,8 @@
 #include "ir_hierarchical_visitor.h"
 #include "main/mtypes.h"
 
+#ifdef __cplusplus
+
 /**
  * \defgroup IR Intermediate representation nodes
  *
@@ -2050,4 +2052,6 @@ extern char *
 prototype_string(const glsl_type *return_type, const char *name,
 		 exec_list *parameters);
 
+#endif /* __cplusplus */
+
 #endif /* IR_H */

src/glsl/ir_hierarchical_visitor.h

@@ -36,6 +36,7 @@ enum ir_visitor_status {
 };
 
 
+#ifdef __cplusplus
 /**
  * Base class of hierarchical visitors of IR instruction trees
  *
@@ -181,5 +182,6 @@ void visit_tree(ir_instruction *ir,
 
 ir_visitor_status visit_list_elements(ir_hierarchical_visitor *v, exec_list *l,
                                       bool statement_list = true);
+#endif /* __cplusplus */
 
 #endif /* IR_HIERARCHICAL_VISITOR_H */

src/glsl/ir_visitor.h

@@ -26,6 +26,7 @@
 #ifndef IR_VISITOR_H
 #define IR_VISITOR_H
 
+#ifdef __cplusplus
 /**
  * Abstract base class of visitors of IR instruction trees
  */
@@ -81,5 +82,6 @@ public:
    virtual void visit(class ir_constant *) {}
    virtual void visit(class ir_call *) {}
 };
+#endif /* __cplusplus */
 
 #endif /* IR_VISITOR_H */