Show whether generated setup.h files changed or not

Don't output "ok" for all files when running update-setup-h, this was
not very informative and possibly misleading. Only show "ok" for the
actually updated files and "unchanged" otherwise.

build/update-setup-h

@@ -65,15 +65,21 @@ update_single_setup_h()
     tmp=$i.$$.tmp
     sed -e "/^\/\* --- start $section options --- \*\/\$/q" $1 > $tmp &&
     cat_common_options_for $setup_inc $1 >> $tmp &&
-    sed -n -e "/^\/\* --- end $section options --- \*\/\$/,\$p" $1 >> $tmp &&
-    mv $tmp $1
+    sed -n -e "/^\/\* --- end $section options --- \*\/\$/,\$p" $1 >> $tmp
 
-    if [ $? -ne 0 ]; then
-        msg " FAILED"
-        error "$0: failed to update file $1"
-        rc=2
+    if cmp -s $1 $tmp; then
+        rm $tmp
+        msg " unchanged"
     else
-        msg " ok"
+        mv $tmp $1
+
+        if [ $? -ne 0 ]; then
+            msg " FAILED"
+            error "$0: failed to update file $1"
+            rc=2
+        else
+            msg " ok"
+        fi
     fi
 }