Adapt CFC Perl build for CPAN dist compat.

The CFC build process has to work properly in both the repo layout and
the layout of a CPAN dist.
Add a `dist` action for CPAN to CFC Perl build.
Make runtime Perl build work with CPAN layout.

Correct some incompatibilities which assumed the repo layout.

Consolidate code which changes behavior for CPAN layouts inside the
module, leaving Build.PL with only straightforward arguments.
Add a `dist` action for the runtime's Perl build.
Prep Clownfish::CFC for independent CPAN dist.

Flesh out prerequisites and other dist metadata.
Update runtime Build.PL prereq, abstract.

Make Clownfish::CFC a CPAN prereq for Clownfish.  Use "Apache Clownfish"
rather than "Clownfish" in dist abstract.
Add MANIFEST.SKIP for CFC Perl build.
Make Storable failures graceful.

Throw exceptions rather than segfault when Clownfish objects are
serialized using Storable.
Switch from CHY_UNUSED_VAR to CFISH_UNUSED_VAR

Also define an unprefixed version of CFISH_UNUSED_VAR if
CFISH_USE_SHORT_NAMES is in use.
Cease using CHY short names
Remove duplicated (and out-of-date) Clownfish.pod.

The correct Clownfish.pod file lives with the Perl bindings for the
runtime.  Remove CFC's bogus copy.
Adjust test for Storable leak

Some versions of Storable seem to leak when dying in a freeze hook
(see RT #97316). Create an extra object for the freeze test so that
subsequent tests won't be confused by an increased refcount.
Define a custom class for thaw test object

On my platform, the local DESTROY method used for the thaw test
didn't have an effect resulting in a warning during cleanup.
Cloak POD for the CPAN dist of Clownfish::CFC.
Cloak POD for the CPAN dist of Clownfish.
Declare variables for XS args

Also prefix the variable names with "arg_" to avoid clashes with other
local variable names.
Declare 'args_ok' variable in XS
Declare 'method' variable in XS
Declare 'retval' variable in XS
Whitespace in generated XS