Use standard OSX brew bottles to speed up test buildbots

.travis.yml

@@ -590,18 +590,24 @@ before_install:
 
 install:
   # Install OS X library dependencies via Homebrew
-  # `brew install --build-bottle` builds libraries for x86_64's lowest common denominator CPU, core2
-  # `sdl2_mixer` requires options from the formula tap https://github.com/mazmazz/homebrew-srb2
-  # `brew postinstall` runs post-install scripts after building a bottle
+  # Do this differently for release buildbots:
+  #     * `brew install --build-bottle` builds libraries for x86_64's lowest common denominator CPU, core2
+  #     * `sdl2_mixer` requires options from the formula tap https://github.com/mazmazz/homebrew-srb2
+  #     * `brew postinstall` runs post-install scripts after building a bottle
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
       brew update;
       brew tap mazmazz/srb2;
     fi;
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-      brew install --build-bottle sdl2 game-music-emu zlib p7zip;
-      brew install --build-bottle mazmazz/srb2/sdl2_mixer --with-flac --with-mpg123;
-      brew postinstall sdl2 game-music-emu zlib p7zip mazmazz/srb2/sdl2_mixer;
-      brew install cmake||true;
+      if [[ "$__DPL_ACTIVE" != "1" ]]; then
+        brew install sdl2 sdl2_mixer game-music-emu p7zip;
+        brew install cmake||true;
+      else
+        brew install --build-bottle sdl2 game-music-emu zlib p7zip;
+        brew install --build-bottle mazmazz/srb2/sdl2_mixer --with-flac --with-mpg123;
+        brew postinstall sdl2 game-music-emu zlib p7zip mazmazz/srb2/sdl2_mixer;
+        brew install cmake||true;
+      fi;
     fi
   - mkdir -p $HOME/srb2_cache