Build GDC master from source

[Nordlöw via D.gnu]

Is it possible to build master or gcc-7 branch of GDC from source 
against GCC?

If so, which of the instructions

- https://wiki.dlang.org/GDC
- https://wiki.dlang.org/GDC/Installation/Generic

should I follow?

Even better, have anybody already got a script that does this?

Moreover, commit

https://github.com/D-Programming-GDC/GDC/commit/2141559f78912b75ef7f9edc6e2d5548ea5ae282

has message "the frontend sources are now at 2.076". Does this 
mean that master compiles a working D compiler compatible with 
DMD 2.076?!!!