Fix Visual Studio errors in GPU2.

- Ambiguous ctor calls in MatDense and MatSparse.
- Explicit type Transform<FPP,GPU2>::iterator (using typename).
	(c:\gitlab-runner\builds\fzds3qmm\0\faustgrp\faust\src\faust_linear_operator\gpu2\faust_Transform_gpu.h(79): warning C4346: 'iterator': dependent name is not a type [C:\Gitlab-Runner\builds\FzDs3qMm\0\faustgrp\faust\build\faust.vcxproj])
- Adding GPU2 cpp files to source files of pyfaust wrapper (fix to undefined symbols).