Don't try gcc on macOS.

Author: abergeron

.travis.yml

@@ -1,8 +1,13 @@
 language: c
 
-os:
-  - linux
-  - osx
+matrix:
+  include:
+    - os: linux
+      compiler: gcc
+    - os: linux
+      compiler: clang
+    - os: osx
+      compiler: clang
 
 addons:
   apt:
@@ -16,10 +21,6 @@ addons:
 #before_install:
 #  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update && brew install cmake; fi
 
-compiler:
-  - clang
-  - gcc
-
 # Build with Debug and Release to flush out build problems
 script:
   - mkdir Debug