func: and file: prefix for `RUBY_DEBUG_LOG_FILTER`

`RUBY_DEBUG_LOG_FILTER` specified only function names but this
patch also check file names for each log events.
If you specify `file:` or `func:` prefix, it's only filter
file names or func names (otherwize check both).

  foo
  # show log when file or func names are mached with foo

  func:foo
  # show log when func name matches foo

  file:foo
  # show log when file name matches foo

  -file:foo,func:bar
  # show log when file name does not contains foo
  #           and func name matches bar

0 files changed, 0 insertions, 0 deletions