Fix fcontext provider for very long lines

The regexp `\s\s+` for fcontext provider does not match very long lines where `filespec` is separated by just one white space.

The error we experienced is:
`Error: Could not prefetch selinux_fcontext provider 'semanage': undefined method `split' for nil:NilClass`

You can experiment a bit here:
http://rubular.com/r/DzLYBbuFMB

This is the new working regexp:
http://rubular.com/r/wOJKIYUwMh