Add a file_known_issue subroutine
Add a file_known_issue subroutine

This subroutine can be used to set a command test as a known issue for
some specific files only.

boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite,gunesacar/tor-browser-bundle-testsuite