Try to get FreeBSD to stop being classified as macOS

Also set things up to use `gmake` instead of `make` since the latter
refers to the incompatible BSD Make rather than GNU Make on BSD.
Hopefully the alias persists across build steps...

.travis.yml

@@ -24,46 +24,48 @@ matrix:
         apt:
           packages:
             - libtommath-dev
-    - os: osx
-      image: xcode8
+    - os: freebsd
       addons:
-        homebrew:
+        pkg:
           packages:
+            - sudo
+            - gmake
             - libtommath
             - concurrencykit
     - os: osx
-      image: xcode11.2
+      image: xcode8
       addons:
         homebrew:
           packages:
             - libtommath
             - concurrencykit
-    - os: freebsd
+    - os: osx
+      image: xcode11.2
       addons:
-        pkg:
+        homebrew:
           packages:
-            - sudo
             - libtommath
             - concurrencykit
 notifications:
   email: false
 before_install:
+  - [ "$(uname)" = "FreeBSD" ] || alias gmake=make
   - |
       git clone https://github.com/concurrencykit/ck.git ${HOME}/ck
       cd ${HOME}/ck
       git checkout 0.6.0
       ./configure PREFIX=/usr
-      make all
-      sudo make install
+      gmake all
+      sudo gmake install
       if [ "$(uname)" = "Linux" ]; then
         sudo ldconfig
       fi
   - |
       git clone https://github.com/justinethier/cyclone-bootstrap.git ${HOME}/cyclone-bootstrap
       cd ${HOME}/cyclone-bootstrap
-      make
-      sudo make install
+      gmake
+      sudo gmake install
 script:
-  - make
-  - sudo make install
-  - make test
+  - gmake
+  - sudo gmake install
+  - gmake test