patch 8.0.1416: crash when searching for a sentence

Problem:    Crash when searching for a sentence.
Solution:   Return NUL when getting character at MAXCOL. (closes #2468)
diff --git a/src/misc2.c b/src/misc2.c
index 87b79fa..fd432cd 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -348,24 +348,29 @@
     int
 inc(pos_T *lp)
 {
-    char_u  *p = ml_get_pos(lp);
+    char_u  *p;
 
-    if (*p != NUL)	/* still within line, move to next char (may be NUL) */
+    /* when searching position may be set to end of a line */
+    if (lp->col != MAXCOL)
     {
-#ifdef FEAT_MBYTE
-	if (has_mbyte)
+	p = ml_get_pos(lp);
+	if (*p != NUL)	/* still within line, move to next char (may be NUL) */
 	{
-	    int l = (*mb_ptr2len)(p);
+#ifdef FEAT_MBYTE
+	    if (has_mbyte)
+	    {
+		int l = (*mb_ptr2len)(p);
 
-	    lp->col += l;
-	    return ((p[l] != NUL) ? 0 : 2);
-	}
+		lp->col += l;
+		return ((p[l] != NUL) ? 0 : 2);
+	    }
 #endif
-	lp->col++;
+	    lp->col++;
 #ifdef FEAT_VIRTUALEDIT
-	lp->coladd = 0;
+	    lp->coladd = 0;
 #endif
-	return ((p[1] != NUL) ? 0 : 2);
+	    return ((p[1] != NUL) ? 0 : 2);
+	}
     }
     if (lp->lnum != curbuf->b_ml.ml_line_count)     /* there is a next line */
     {