Add string display for vpiEnumTypespec and create hook for UdpDefn iteration.

This patch adds vpiEnumTypespec to the list so that vpi_get_str(vpiType, ...)
returns an appropriate string when an enum type is passed.

It also adds the initial hook to allow iteration (global) over the UDP
definitions. This along with table traversal will be needed to free the
memory allocated when the UDP definition is created. Ultimately this
will all the UDP test to be valgrind clean.

vpi_user.h

@@ -288,6 +288,7 @@ typedef struct t_vpi_delay  {
 #define vpiSysTaskCall 57
 #define vpiTask        59
 #define vpiTimeVar     63
+#define vpiUdpDefn     66
 #define vpiUserSystf   67
 #define vpiNetArray   114
 #define vpiIndex       78

vvp/vpi_priv.cc

@@ -262,6 +262,8 @@ static const char* vpi_type_values(PLI_INT32 code)
 	    return "vpiByteVar";
 	  case vpiConstant:
 	    return "vpiConstant";
+	  case vpiEnumTypespec:
+	    return "vpiEnumTypespec";
 	  case vpiFunction:
 	    return "vpiFunction";
 	  case vpiIntVar:
@@ -1047,6 +1049,13 @@ vpiHandle vpi_handle(PLI_INT32 type, vpiHandle ref)
       return res;
 }
 
+static vpiHandle vpip_make_udp_iterator()
+{
+// HERE: Add support for iterating over UDP definitions.
+//       See 26.6.16 (page 400 in 1364-2005).
+      return 0;
+}
+
 /*
  * This function asks the object to return an iterator for
  * the specified reference. It is up to the iterate_ method to
@@ -1058,6 +1067,9 @@ static vpiHandle vpi_iterate_global(int type)
 	  case vpiModule:
 	    return vpip_make_root_iterator();
 
+	  case vpiUdpDefn:
+	    return vpip_make_udp_iterator();
+
 	  case vpiUserSystf:
 	    return vpip_make_systf_iterator();
       }