Patch for (potential) uninitalized variable num_lines

Static analysis indicates that there is a feasible
code path in LayoutParagraphs (called in GetNarrowWidth)
which will not result in calling Layout which will
initialize the variable num_lines.  Initialize the
variable num_lines just in case (and make the
analyzer happy).
(cherry picked from commit a5388fb)

Signed-off-by: Stuart Morgan <smorgan@mythtv.org>

Fixes #11553

mythtv/libs/libmythui/mythuitext.cpp

@@ -612,7 +612,8 @@ bool MythUIText::GetNarrowWidth(const QStringList & paragraphs,
 {
     qreal    height, last_line_width, lines;
     int      best_width, too_narrow, last_width = -1;
-    int      num_lines, line_height = 0;
+    int      num_lines = 0;
+    int      line_height = 0;
     int      attempt = 0;
     Qt::TextElideMode cutdown = m_Cutdown;
     m_Cutdown = Qt::ElideNone;