[perl #39085] [CAGE] pmc - make pmc2c.pl extract function declarations

[chromatic via RT]

One question is whether we generate POD from the PMC files, from the C
files, or from something else.  If I ever read the PMC documentation
outside of my editor while working on the PMC, I generally read it
through perldoc src/pmc/some_pmc.pmc.  In that case, generating the
documentation from the PMC file doesn't help me.

This may argue for making a tool to display ops/PMC documentation
elsewise, however.

-- c