Apply the unpace rule into embedded comments

[Agent Zhang]

Hi, there~

While I was adding tests to t/syntax/comments.t in the Pugs test suit
this afternoon, I suddenly came up with this form of embedded
comments:

my $foo = #\ (this is a comment) 42;
is $foo, 42;

Now that we have the excellent unspace rule, why can't we use it
consistently with the embedded comment syntax?

As Luke said on #perl6, although this is not an important issue at
all, it's an interesting corner case in Perl 6's syntax. :=)

Regards,
Agent