[PATCH 3/2 xserver] travis: Enable ccache.

[Adam Jackson]

On Thu, 2017-06-01 at 13:59 -0700, Eric Anholt wrote:
> We bind-mount the cache directory into the container.  Cuts build time
> from about 4 minutes to 2.
> 
> Signed-off-by: Eric Anholt <eric at anholt.net>

remote: I: patch #159533 updated using rev fda2b064a0ebd223e8a39fd19f5c5ad1da0776e8.
remote: I: patch #159534 updated using rev 01dfb65ee2e34148718d3f95dfd4629024edba84.
remote: E: failed to find patch for rev d82c3cee02a99cf7861d1effaa5c7d38683a7783.
remote: I: 2 patch(es) updated to state Accepted.
To ssh://git.freedesktop.org/git/xorg/xserver
   75bf302ed..d82c3cee0  master -> master

Failure there is from the .travis.yml script name fixup.

- ajax