Remove osx, do 32/64 gcc/clang.

.travis.yml

@@ -1,14 +1,14 @@
 language: c
 dist: trusty
+compiler:
+    - gcc
+    - clang
 
 matrix:
     include:
         - os: linux
           env: BUILD=x86_64-linux-gnu
 
-        - os: linux
-          compiler: clang
-
         - os: linux
           env: BUILD=i686-linux-gnu CFLAGS=-m32
           addons:
@@ -16,8 +16,6 @@ matrix:
                   packages:
                       - gcc-multilib
 
-        - os: osx
-
 script:
     - ./bootstrap && ./configure && make
     - file src/openocd