Subtitles: Fix layout to stay within the safe area.

Subtitle backgrounds were sometimes extending to the left of the safe
area, which is not what was intended.  Shift subtitles by that amount
to compensate.

Author: stichnot

mythtv/libs/libmythtv/subtitlescreen.cpp

@@ -1232,11 +1232,13 @@ bool FormattedTextSubtitle::Draw(QList<MythUIType*> *imageCache,
             QSize chunk_sz = (*chunk).CalcSize();
             if ((*chunk).format.GetBGAlpha())
             {
+                int padding = font.maxWidth() * PAD_WIDTH;
+                if (first)
+                    x += padding;
                 QBrush bgfill = QBrush((*chunk).format.GetBGColor());
                 QRect bgrect(x, y, chunk_sz.width(), height);
                 if (first)
-                    bgrect.setLeft(bgrect.left() + x_adjust -
-                                   font.maxWidth() * PAD_WIDTH);
+                    bgrect.setLeft(bgrect.left() + x_adjust - padding);
                 MythUIShape *bgshape = new MythUIShape(parent,
                         QString("subbg%1x%2@%3,%4")
                                      .arg(chunk_sz.width())