[PATCH xserver] travis: Fix OSX build

[Jon Turney]

Turn off homebrew autoupdating before installing ccache, to avoid:

/usr/local/Homebrew/Library/Homebrew/brew.rb:12:in `<main>': Homebrew must
be run under Ruby 2.3! You're running 2.0.0. (RuntimeError)

Signed-off-by: Jon Turney <jon.turney at dronecode.org.uk>
---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 498391d1d..bc54f3bc1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,7 +12,7 @@ before_install:
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then docker pull jturney/xserver-travis:v2 ; fi
 
 install:
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install ccache ; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then HOMEBREW_NO_AUTO_UPDATE=1 brew install ccache ; fi
 
 before_script:
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then echo FROM jturney/xserver-travis:v2 > Dockerfile ; fi
-- 
2.14.2