patch 8.0.0425: build errors when building without folding

Problem:    Build errors when building without folding.
Solution:   Add #ifdefs. (John Marriott)

src/diff.c

@@ -2616,7 +2616,6 @@ diff_get_corresponding_line(buf_T *buf1, linenr_T lnum1)
     return lnum;
 }
 
-#if defined(FEAT_FOLDING) || defined(PROTO)
 /*
  * For line "lnum" in the current window find the equivalent lnum in window
  * "wp", compensating for inserted/deleted lines.
@@ -2656,6 +2655,5 @@ diff_lnum_win(linenr_T lnum, win_T *wp)
 	n = dp->df_lnum[i] + dp->df_count[i];
     return n;
 }
-#endif
 
 #endif	/* FEAT_DIFF */

src/edit.c

@@ -541,8 +541,8 @@ edit(
 
     /*
      * Handle restarting Insert mode.
-     * Don't do this for "CTRL-O ." (repeat an insert): we get here with
-     * restart_edit non-zero, and something in the stuff buffer.
+     * Don't do this for "CTRL-O ." (repeat an insert): In that case we get
+     * here with something in the stuff buffer.
      */
     if (restart_edit != 0 && stuff_empty())
     {
@@ -1453,10 +1453,14 @@ doESCkey:
 
 docomplete:
 	    compl_busy = TRUE;
+#ifdef FEAT_FOLDING
 	    disable_fold_update++;  /* don't redraw folds here */
+#endif
 	    if (ins_complete(c, TRUE) == FAIL)
 		compl_cont_status = 0;
+#ifdef FEAT_FOLDING
 	    disable_fold_update--;
+#endif
 	    compl_busy = FALSE;
 	    break;
 #endif /* FEAT_INS_EXPAND */

src/option.c

@@ -4535,8 +4535,11 @@ do_set(
 		 * "wrap" gets set. */
 		if (curwin->w_p_diff
 			&& opt_idx >= 0  /* shut up coverity warning */
-			&& (options[opt_idx].indir == PV_FDM
-			    || options[opt_idx].indir == PV_WRAP))
+			&& (
+#ifdef FEAT_FOLDING
+			    options[opt_idx].indir == PV_FDM ||
+#endif
+			    options[opt_idx].indir == PV_WRAP))
 		    goto skip;
 #endif
 	    }

src/syntax.c

@@ -1183,11 +1183,12 @@ syn_stack_free_block(synblock_T *block)
     void
 syn_stack_free_all(synblock_T *block)
 {
+#ifdef FEAT_FOLDING
     win_T	*wp;
+#endif
 
     syn_stack_free_block(block);
 
-
 #ifdef FEAT_FOLDING
     /* When using "syntax" fold method, must update all folds. */
     FOR_ALL_WINDOWS(wp)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    425,
 /**/
     424,
 /**/