C: detect maybe::next::method

fixes issue 326.
Note that there is no maybe::next equivalent in 5.8, so we just use a NEXT::DISTINCT method
C: improve next::maybe/NEXT detection and testcase a bit

NEXT can have any method name afterwards. Also mark the package and mro
t/testc.sh: fix testcase for i24 to 124, had duplicate 224
C 1.46_02: max 3x walkall, recursively dump included but not yet dumped packages

at inc_cleanup()
rename %saved to %dumped_package,
fixes issue 340 where IO::Socket::INET6 and its deps are not being dumped,
but this change looks problematic.
C: improve walkall, skip core packages

Still: inc-340 causes these -O3 regressions: 45 68
C inc-i340: improve skip_pkg logic

and observe -fno-warnings.

fixes the 45 and 64 regressions,
but breaks (on 5.18):
  200 run-time utf8 hek
and 46 (-fstash) on 5.14 (hek asserts)
C inc-i340: fix -fstash regressions but still not good enough

all 5.14 tests pass now, 5.18 200 also,
but we got many testcore regressions:
t/C-COMPILED/CORE--base--lex.t                         (Wstat: 1536 Tests: 23 Failed: 6)
  Failed tests:  8-9, 12, 18-19, 22
t/C-COMPILED/CORE--mro--next_edgecases.t               (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--closure.t                       (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21
t/C-COMPILED/CORE--op--dbm.t                           (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21
t/C-COMPILED/CORE--op--inccode.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--length.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--sigdispatch.t                   (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--undef.t                         (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--re--charset.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--re--substr.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
inc-i340: inc cleanup with %dumped_package, add optional -fwalkall

use the real check for %INC cleanup:
%dumped_package (what we really dumped), not %include_package (what we wanted to dump)
do the post walker into an -fwalkall option, which should cause no regressions and fix 340
CC crashes, try to refactor WIP

Now failing regressions are only:
  t/issue31.t   1
  t/issue71.t   3
  t/issue59.t   3
  t/e_perlcc.t  22 (added XS dep)
and:
t/C-COMPILED/CORE--base--lex.t                         (Wstat: 1536 Tests: 23 Failed: 6)
  Failed tests:  8-9, 12, 18-19, 22
t/C-COMPILED/CORE--mro--next_edgecases.t               (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--closure.t                       (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21
t/C-COMPILED/CORE--op--dbm.t                           (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21
t/C-COMPILED/CORE--op--inccode.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--length.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--sigdispatch.t                   (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--op--undef.t                         (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--re--charset.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
t/C-COMPILED/CORE--re--substr.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
C: fix CORE--base--lex.t regression
C: change should_save OO heuristic: skip our packages

do not mark OO packages automatically which are included by B::C
C: fix %dumped_package, add walk_syms debugging

%dumped_package was not added in walksymtable, as the prefix always ended in "::"
C: tune %dumped_package

still the same core regressions, much less testfast failures
set dumped_package in savecv, and in "force saving of XSLoader"

skip force warnings when Carp is not dumped (not included).

remaining regressions:
t/issue24.t     (dbm)
  Failed tests:  2-3
t/cc.t          (-fstash)
  Failed test:  46

core: (mostly static warn overwrites)
t/C-COMPILED/CORE--mro--next_edgecases.t               (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3 message for your changes. Lines starting
t/C-COMPILED/CORE--mro--isarev==SIG-0.t                (Wstat: 0 Tests: 23 Failed: 0)
  TODO passed:   7
t/C-COMPILED/CORE--op--closure.t                       (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21h your local commits)
  Non-zero exit status: 4
t/C-COMPILED/CORE--op--dbm.t                           (Wstat: 1024 Tests: 23 Failed: 4)
  Failed tests:  10-11, 20-21
  Non-zero exit status: 4
t/C-COMPILED/CORE--op--inccode.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
t/C-COMPILED/CORE--op--length.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
t/C-COMPILED/CORE--op--sigdispatch.t                   (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
t/C-COMPILED/CORE--op--undef.t                         (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
t/C-COMPILED/CORE--re--charset.t                       (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
t/C-COMPILED/CORE--re--pat_advanced==SIG-330.t         (Wstat: 0 Tests: 23 Failed: 0)
  TODO passed:   17
t/C-COMPILED/CORE--re--substr.t                        (Wstat: 768 Tests: 23 Failed: 3)
  Failed tests:  17-18, 22
  Non-zero exit status: 3
C/CC: skip earlier in should_save, add CC-specific deps

breaks a few more core tests, but CC is now really slim
C: unconst warnings::Bits strings with -O3

They are written to when warning masks change when using warnings, and
caused segfaults. See issue 340. E.g. t/CORE/op/undef.t with -O3 and many more
CORE tests. This error came up when we added proper INC deps in inc-i340-CC, where
warnings were statically compiled in

Fixed in core:
    t/C-COMPILED/CORE--mro--next_edgecases.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--op--inccode.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--op--length.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--op--sigdispatch.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--op--undef.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--re--charset.t
      Failed tests:  17-18, 22
    t/C-COMPILED/CORE--re--substr.t
      Failed tests:  17-18, 22

Remaing core regressions:
    t/C-COMPILED/CORE--op--closure.t
      Failed tests:  10-11, 20-21
    t/C-COMPILED/CORE--op--dbm.t
      Failed tests:  10-11, 20-21
C: fix dbmopen: store $INC{AnyDBM_File} and TIEHASH

also resolve the correct $AnyDBM_File::ISA[0] by doing a compile-time AnyDBM_File->import
t/CORE: add is_perlcc_compiled(), use in op/dbm.t and op/closure.t

B::C:: is not stored anymore. check now for B::C in @DynaLoader::dl_modules

Fixes the remaining testcore regressions
t/issue340.t: added
Changes: document changes from inc-i340-CC branch
module updates for B-C-1.46_02. no changes