C: Fix package destruction, -1 GV refcount

The GV refcount was one to high (B::walksymtable) which prevented
package destruction methods from being called (#197, #208, #254, #280)

Now failing: #46
testcore: add temp files to .gitignore and CLEAN
testcore: pass optimizations to subtests, accept BC_OPT="...", defaults to -O0 and -O3

proper optimization handling
t/testc.sh,cc_harness: support -A for -DALLOW_PERL_OPTIONS

improve cc_harness arg handling: -q and -d not only as first args
C: fix -1 GV refcount changes

increment GP properly (revert old change)
log.modules-5.019008-nt update for 1.43_07 0c17ff5 (worse)

2 regressions: namespace::clean MooseX::Types
log.modules-5.019008-nt update for 1.43_08 7f33fee

no changes
log.modules-5.008009 added (all ok)
C: fix GV refcnt: no extra B::walksymtable reference

revert old GV refcnt change.
compared with pure-perl refcounts
perlcc 2.17: new option -A for -DALLOW_PERL_OPTIONS

sync with t/testc.sh -A
wontfix t/CORE/comp/package.t #182 undef stash -> __ANON__
reformat tests for #254
C 1.43_09: sv_clean_objs for -O3, add PL_sv_arenaroot

incr PL_sv_objcount, causes sv_clean_objs to run DESTROY methods
(incremented at BEGIN time and by sv_bless)

always call my_perl_destruct or fast_perl_destruct,
which either prepends static svs to the sv_arenaroot,
at global destruction (not before as this would slow down del_sv)
or for -O3 fast_perl_destruct do a manual curse (sv_clean)
and the IO and dynamic sv cleanup.

move my_perl_destruct or fast_perl_destruct declaration to the front.
print the arena chains and sizes on -DD
  (static typically 3x smaller than the dynamic)

also call PL_exitlist functions with -O3
use %p, not %x to avoid clang -Wformat warnings

CC: store *DESTROY->next->type for sv_clean_objs
    change -fno-destruct as CC default >=5.10

fixes #197 and #208,
still failing -O3 our #208 and #254
C: improve sv_clean_objs for -O3

sv_clean (ie curse) only SvOBJECT and deref var, usually a scalar blessed var
op/magic-27839.t: fix undefined pv and fullname warnings #292
CORE--op--ref==BADTEST-197-285-286.t CORE--op--magic_phase==BADTEST-208.t

BADPLAN => BADTEST. tests do run through now
make clean: add Io_argv* from core tests
make clean: more core tests leftovers
t/testc.sh: add testcase for #289, again a CvCVGV_RC assert

but unlike 235 which had the CVf_CVGV_RC flag set
C: fix #289, add GV->CV backref magic

simplify CvFLAGS handling to filter out CVf_DYNFILE and CVf_CVGV_RC
fix too high REFCNT for CVs (cross-checked with pure-perl)
run-time CvCVGV_RC_off for backref magic CVs

now we have new cv_undef failures to investigate (perlio, attributes, ...)