svg_loader: fix vector memory leaks.

svg_loader: fix vector memory leaks.

vector is designed for c++ syntaxes,
it works properly when c++ memory allocator is applied,

Here svg_loader uses c style structures which allocated using malloc()/calloc().
That brings the memory broken of stl vectors.

So, we replaced it with our customized SvgVector to easily fix it.

Change-Id: Iccf5090b13322671893bb8b185bba6d8253e96f5