Add flag for enabling sccache

[MarshallOfSound]

Use with --sccache

[alexeykuzmin]

We should expose cc_wrapper rather than hardcoding sccache, it might make sense to use some other wrapper/s, e.g. regular ccache.

I think that having --sccache as a shortcut for --cc_wrapper=sccache is a good thing.

[alexeykuzmin]

I think that having --sccache as a shortcut for --cc_wrapper=sccache is a good thing.

I mean something like that:

cc_wrapper_group = parser.add_mutually_exclusive_group()
cc_wrapper_group.add_argument('--cc_wrapper', help="...")
cc_wrapper_group.add_argument('--ccache',
                              action='store_const', const='ccache', dest='cc_wrapper',
                              help="...")
cc_wrapper_group.add_argument('--sccache',
                              action='store_const', const='sccache', dest='cc_wrapper',
                              help="...")

[alexeykuzmin]

We should expose cc_wrapper rather than hardcoding sccache, it might make sense to use some other wrapper/s, e.g. regular ccache.

@nornagon done