awk: do not use a copy of g_progname for node->l.new_progname

We never destroy g_progname's, the strings still exist, no need to copy

function                                             old     new   delta
chain_node                                           104      97      -7
Signed-off-by: NDenys Vlasenko <vda.linux@googlemail.com>

editors/awk.c

@@ -179,7 +179,7 @@ typedef struct node_s {
 		struct node_s *n;
 		var *v;
 		int aidx;
-		char *new_progname;
+		const char *new_progname;
 		regex_t *re;
 	} l;
 	union {
@@ -1501,7 +1501,7 @@ static node *chain_node(uint32_t info)
 	if (seq->programname != g_progname) {
 		seq->programname = g_progname;
 		n = chain_node(OC_NEWSOURCE);
-		n->l.new_progname = xstrdup(g_progname);
+		n->l.new_progname = g_progname;
 	}
 
 	n = seq->last;