[perl #44171] [TODO] config/auto/attributes.pm: Write unit tests

[James Keenan via RT]

I had some off-list conversations with ptc about a month ago about these
issues.  Running the step with --verbose-step indicated that attributes
that the compiler does not recognize do not get added to the 'ccflags'
attribute.  Cf. patch applied to trunk: 
http://perlcabal.org/svn/parrot/revision/?rev=23364.