[ccache] Using a shared ccache in cmake environment (linux)

[Steffen Dettmer]

Hi,

* On Tue, Mar 17, 2020 at 3:54 PM Paul Smith <paul at mad-scientist.net> wrote:
> You don't say which compiler you're using but if you're using GCC you
> can consider using the -ffile-prefix-map option to avoid these issues.

Thanks for the tip! Your are right, this is for gcc, sorry that I
didn't mention.

Unfortunately only gcc-8, but also I have to support 4.4.3, 4.5.1 and others.
These have only -fdebug-prefix-map (which I use).

Steffen