MINOR: stick-tables: Add GPT0 access

This patch adds acces to GPT0. The access can be done with http and
tcp actions, and through a converter.
diff --git a/include/types/action.h b/include/types/action.h
index fd264cb..5d1b250 100644
--- a/include/types/action.h
+++ b/include/types/action.h
@@ -130,6 +130,10 @@
 			const char *name;
 			enum vars_scope scope;
 		} vars;
+		struct {
+			int sc;
+			long long int value;
+		} gpt;
 		struct track_ctr_prm trk_ctr;
 		struct {
 			void *p[4];