add -use_wildcard_cache flag

% time ./repo/android.sh kati -c -use_wildcard_cache=false > /dev/null
find: `dummy': No such file or directory
find: `dummy': No such file or directory
fatal: Not a git repository: 'packages/apps/Camera2/.git'
./repo/android.sh kati -c > /dev/null  36.02s user 45.50s system 132% cpu 1:01.40 total
% time ./repo/android.sh kati -c -use_wildcard_cache=true > /dev/null
find: `dummy': No such file or directory
find: `dummy': No such file or directory
fatal: Not a git repository: 'packages/apps/Camera2/.git'
./repo/android.sh kati -c -use_wildcard_cache > /dev/null  34.58s user 39.02s system 131% cpu 55.778 total

fix testcase/wildcard_cache.mk
5 files changed