The glyphs are not stored in a fixed 64x64px tile anymore.
Glyphs are stored in area equal to <glyph_width> + 10 (margin) x 64px.
Allocation is now done with QSGAreaAllocator.
When glyph recycling is needed, unused glyphs are freed until the new
glyph can fit in the cache.

Change-Id: I179a8f17bfe35468bdb63bca5113ea4d0f06c414
Reviewed-by: Yoann Lopes <yoann.lopes@nokia.com>