Fix bug in HDMX table (from stuartg's code review)

git-svn-id: http://sfntly.googlecode.com/svn/trunk/cpp/src@106 672e30a5-4c29-85ac-ac6d-611c735e0a51
diff --git a/sfntly/table/core/horizontal_device_metrics_table.cc b/sfntly/table/core/horizontal_device_metrics_table.cc
index 34d03e6..50b0cf5 100644
--- a/sfntly/table/core/horizontal_device_metrics_table.cc
+++ b/sfntly/table/core/horizontal_device_metrics_table.cc
@@ -102,8 +102,8 @@
   if (num_glyphs < 0) {
 #if !defined (SFNTLY_NO_EXCEPTION)
     throw IllegalArgumentException("Number of glyphs can't be negative.");
-    return;
 #endif
+    return;
   }
   num_glyphs_ = num_glyphs;
   HorizontalDeviceMetricsTable* table =