For CI - address the limitation of Travis CI's caching logic.

Travis CI is not able to find the matching cache file in their cache store for the newly created CI mirror branches for new topic branch. As the result, the initial CI jobs run without the benefit of the ccache. For OSX and iOS universal binary builds, this would usually cause our custom interrupt mechanism to be triggered. To avoid that, when cache size is 0 then we configure the build system to only build for 64-bit arch. Basically half the number of archs in the universal build.

.travis.yml

@@ -304,7 +304,6 @@ before_script:
   - export COMMIT_MESSAGE=$(git log --format=%B -n 1 $TRAVIS_COMMIT)
   - export TAG=$(git describe --exact-match $TRAVIS_COMMIT 2>/dev/null); if [[ $TAG =~ [[:digit:]]+\.[[:digit:]]+ ]]; then export RELEASE_TAG=$TAG; fi
   - if [ $XCODE ] && ([ $RELEASE_TAG ] || (! [[ $TRAVIS_BRANCH =~ [^-]+-[^-]+-CI ]] && echo $COMMIT_MESSAGE |grep -cq '\[ci package\]')); then export PACKAGE_UPLOAD=1; fi
-  - if [ $XCODE ] && echo $COMMIT_MESSAGE |egrep -cq '\[(ccache clear|xcode 64bit only)\]'; then export XCODE_64BIT_ONLY=1; fi
   - travis_retry brew update >/dev/null
   - which cmake >/dev/null 2>&1 || cmake=cmake
   - if [ $PACKAGE_UPLOAD ]; then doxygen='doxygen graphviz'; fi
@@ -314,7 +313,7 @@ before_script:
   - 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
+  - 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; if echo $COMMIT_MESSAGE |egrep -cq '\[(ccache clear|xcode 64bit only)\]' || [[ $(ccache -s |grep 'files in cache' |rev |cut -d' ' -f1 |rev) == '0' ]]; then export XCODE_64BIT_ONLY=1; fi; fi
   - rake ci_setup_cache
 script: rake ci && if [ $PACKAGE_UPLOAD ]; then rake ci_package_upload; fi && rake ci_timer
 after_script: rake ci_teardown_cache