[master] 431456a Update xcode and travis image

[Federico G. Schwindt]

commit 431456a9d5fa0c8b53ae90d943a30eb5bc5d991f
Author: Federico G. Schwindt <fgsch at lodoss.net>
Date:   Wed Jan 10 14:00:00 2018 +0000

    Update xcode and travis image

diff --git a/.travis.yml b/.travis.yml
index 3db4182..ef8a2ee 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 ---
 sudo: required
 language: c
-group: deprecated-2017Q3
 matrix:
   include:
   - os: linux
@@ -15,7 +14,7 @@ matrix:
     compiler: clang
     env: CLANG=5.0 SAN_FLAGS="--enable-asan --enable-ubsan"
   - os: osx
-    osx_image: xcode9
+    osx_image: xcode9.2
     compiler: clang
   allow_failures:
   - os: osx