GenericSalLayout: manage the collection of GlyphItem with a vector.

There was a TODO to replace a manually managed array of Glyphs
to use std::list

a GlyphItem is 36 bytes long. the colleciton of GlyphItems is
mostly used in a sequential access. random insert/delete are fairly rare.
using std::list would increase the size by at least 8 to 16 bytes per
element (depending on the size of void*) (25 to 50% overhead)
and would greatly degrade data locality for most iterations loops.
so std::vector seems more appropriate here.

vcl/inc/sallayout.hxx

@@ -374,9 +374,7 @@ protected:
     bool            GetCharWidths( sal_Int32* pCharWidths ) const;
 
 private:
-    GlyphItem*      mpGlyphItems;   // TODO: change to GlyphList
-    int             mnGlyphCount;
-    int             mnGlyphCapacity;
+    GlyphVector     m_GlyphItems;
     mutable Point   maBasePoint;
 
     // enforce proper copy semantic