st/mesa: add extern "C" to st_program.h

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/mesa/state_tracker/st_program.h

@@ -41,6 +41,11 @@
 #include "st_glsl_to_tgsi.h"
 
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
 /** Fragment program variant key */
 struct st_fp_variant_key
 {
@@ -347,4 +352,8 @@ extern void
 st_print_current_vertex_program(void);
 
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif