Set sub names when calling defer_sub

[autarch]

I was trying to fix https://rt.cpan.org/Ticket/Display.html?id=119534. This doesn't fix it, but I think these changes are still worth making. AFAICT, Sub::Defer really wants us to pass in a sub name.

[autarch]

The test failures are a bit confusing. The "changes doesn't have content" failure is sort of a false failure, since the Changes files doesn't have a listing for this version yet, right? But somehow it is still checking for release notes for 0.50. My EnsureChangesHasContent plugin would get this right, I think ;)

The 12_wrapper-definition.t failure is very confusing. It's some sort of heisenfailure. I can reproduce it by running the code multiple times. I think it might have to do with the fact that the test code uses ->can to get a coderef to the to_X sub. Then Sub::Defer replaces that sub by name, but the coderef itself still points to the old deferred sub. I don't understand why it sometimes works though.

[autarch]

Actually, I think the 12 failure is something else, where the use of Sub::Defer simply doesn't work properly with the wrapper functionality, but somehow it accidentally works in some cases. I could use some help from someone who understands the internals of MX::Types a little better.