Test builds with newer g++, clang and OS X on Travis CI

Configure the build matrix to test building on more platforms and using clang
as well and also test C++11 builds using both g++ and clang.

.travis.yml

@@ -5,7 +5,22 @@
 language: cpp
 sudo: required
 
-compiler: gcc
+matrix:
+    include:
+        - compiler: gcc
+        - compiler: gcc
+          env: wxCONFIGURE_FLAGS="--disable-precomp-headers --enable-monolithic"
+        - dist: trusty
+          compiler: gcc
+        - dist: trusty
+          compiler: gcc
+          env: wxCONFIGURE_FLAGS="--enable-cxx11 --enable-stl"
+        - dist: trusty
+          compiler: clang
+          env: wxCONFIGURE_FLAGS="--disable-shared"
+        - os: osx
+          compiler: clang
+          env: wxCONFIGURE_FLAGS="--enable-cxx11"
 
 branches:
     only:
@@ -21,12 +36,6 @@ notifications:
 
 before_install: ./build/tools/before_install.sh
 
-env:
-    - wxCONFIGURE_FLAGS=
-    - wxCONFIGURE_FLAGS="--disable-shared"
-    - wxCONFIGURE_FLAGS="--disable-precomp-headers --enable-monolithic"
-    - wxCONFIGURE_FLAGS="--enable-stl" CXXFLAGS=-std=c++0x
-
 script:
     - echo 'Configuring...' && echo -en 'travis_fold:start:script.1\\r'
     - ./configure --disable-optimise $wxCONFIGURE_FLAGS

build/tools/before_install.sh

@@ -2,7 +2,7 @@
 #
 # This script is used by Travis CI to install the dependencies before building
 # wxWidgets but can also be run by hand if necessary but currently it only
-# works for Ubuntu 12.04 and 14.04 used by Travis.
+# works for Ubuntu 12.04 and 14.04 and OS X used by Travis builds.
 
 SUDO=sudo
 
@@ -13,4 +13,9 @@ case $(uname -s) in
             $SUDO apt-get install -y libcppunit-dev libgtk2.0-dev libnotify-dev
         fi
         ;;
+
+    Darwin)
+        brew update
+        brew install cppunit --universal
+        ;;
 esac