For CI - attempt to fix the brew uninstall step due to invalid input.

[ci only: OSX] [skip appveyor]

.travis.yml

@@ -366,9 +366,9 @@ before_script:
   - if [ $PACKAGE_UPLOAD ]; then doxygen='doxygen graphviz'; fi
   - travis_retry brew install ccache $cmake $doxygen
   - whitelist='brew-cask ccache cmake doxygen graphviz libpng libyaml openssl pkg-config readline'
-  - for f in $(brew list); do [[ $whitelist =~ $f ]] || travis_retry brew uninstall --force $f; done
-  - for f in $(brew cask list); do [[ $whitelist =~ $f ]] || travis_retry brew cask uninstall --force $f; done
-  - travis_retry brew cleanup
+  - for f in $(brew list); do [[ $whitelist =~ $f ]] || brew uninstall --force $f; done
+  - for f in $(brew cask list |grep -v Uninstalling); do [[ $whitelist =~ $f ]] || brew cask uninstall --force $f; done
+  - brew cleanup
   - export PATH=$(brew info ccache |grep -o '\S*lib\S*'):$PATH
   - if [ $XCODE ]; then sudo cp -p $(which ccache) $(dirname $(xcodebuild -find-executable clang)) && for compiler in clang clang++; do path=$(xcodebuild -find-executable $compiler); sudo mv $path{,.orig} && sudo ln -sf $(dirname $path)/clang.orig /usr/bin/$compiler && sudo ln -sf ccache $path; done && if [ $IOS ]; then redundant=AppleTV,Watch; elif [ $TVOS ]; then redundant=iPhone,Watch; else redundant=iPhone,AppleTV,Watch; fi && eval sudo rm -rf /Applications/Xcode.app/Contents/Developer/Platforms/{$redundant}{OS,Simulator}.platform; fi
   - rake ci_setup_cache