correct an rng mistake in 6e0d55df from Jan 2019

Reported by entrez

include/extern.h

@@ -2349,6 +2349,7 @@ extern long nhrand(void);
 #endif
 extern int rn2(int);
 extern int rn2_on_display_rng(int);
+extern int rnd_on_display_rng(int);
 extern int rnl(int);
 extern int rnd(int);
 extern int d(int, int);

src/do_name.c

@@ -1332,7 +1332,7 @@ do_oname(struct obj *obj)
         /* for "the Foo of Bar", only scuff "Foo of Bar" part */
         bufp = !strncmpi(buf, "the ", 4) ? (buf + 4) : buf;
         do {
-            wipeout_text(bufp, rn2_on_display_rng(2), (unsigned) 0);
+            wipeout_text(bufp, rnd_on_display_rng(2), (unsigned) 0);
         } while (!strcmp(buf, bufcpy));
         pline("While engraving, your %s slips.", body_part(HAND));
         display_nhwindow(WIN_MESSAGE, FALSE);

src/rnd.c

@@ -167,6 +167,12 @@ rnd(register int x)
     return x;
 }
 
+int
+rnd_on_display_rng(register int x)
+{
+    return rn2_on_display_rng(x) + 1;
+}
+
 /* d(N,X) == NdX == dX+dX+...+dX N times; n <= d(n,x) <= (n*x) */
 int
 d(register int n, register int x)