Import 'import' instead of inheriting it

[ilmari]

This fixes errors when the first use of Try::Tiny happens during global
destruction on Perl >= 5.10.0.

The problem is that the inheritance caches don't get invalidated during
global destruction, and base.pm skips classes that the calling class
already inherits from, thus populating an initial empty inheritance
cache, which doesn't get invalidated when it adds the class to @isa.

[doy]

Do you have a test for this? I can't seem to reproduce it (I get this same result on all perls from 5.8 to 5.18):

$ perl -e'{ package Foo; sub DESTROY { require Try::Tiny; Try::Tiny::try { warn "foo" } } }; our %foo; bless \%foo, "Foo";' 
foo at -e line 1 during global destruction.

[ilmari]

The problem is caused when a module importing try/catch from Try::Tiny is loaded during global destruction, in which case the subs aren't exported to it, since 'use base' doesn't work.

Because exceptions during global destruction are converted to warnings and don't affect the exit status, testing would involve using Capture::Tiny, which until yesterday (version 0.23) didn't install on 5.6. Now that that's fixed, I'll gladly write some tests, if that's an acceptable test prereq.

[doy]

Yes, that's fine - just make it an author dependency (and have the test skip if it's not installed).