modernize core modules

[rurban]

use proper sigs where ever possible in our internal libraries.

1st, this catches arity and wrong argument types at compile-time.
2nd, this calling convention is faster than via @_
3rd, enhances the signatures #7 test coverage.

See branch featurex/gh7-sig+libs https://github.com/perl11/cperl/commits/featurex/gh7-sig+libs

[rurban]

As of f946e8bf05db6d0470dc2d040d4a53f28870c749 we are down to 4 test failures,
caused by tailcalls to signatures via goto.

• ../cpan/Test-Simple/t/auto.t (goto sig via AUTOLOAD)
• ../cpan/Test-Simple/t/capture.t (goto sig via AUTOLOAD)
• ../cpan/Test-Simple/t/run_test.t (goto sig via AUTOLOAD)
• ../lib/perl5db.t (nextstate op between entersub and signature, fixed with signatures with -d: no nextstate before signature #109)

but I cannot just disable goto/AUTOLOAD when jumping to a signature.

[rurban]

Done for a long time already. Published with v5.24.0c