[build] -mabi=64 for mips/ppc64 with --m=64

Do the right default for --m=64 on ppc/mips with gcc multilib.
These default to 32-bit, and need -mabi=64.
See GH #1110.

tested only on mips64 so far. ppc64 later, arm64 (aarch64) probably
also. sparc64 is different.
[build] --{en,dis}able-static

enable turns off parrot_is_shared, links to static libparrot

disable turns off compiling a static libparrot.a at all.
  the config key libparrot_static is empty then.

See GH #1104
coro: refactor return code. problem: wrong continuation

let Parrot_sub_continuation_rewind_environment return from_sub
for continuation.invoke.
let yield carry a 2nd state: 2 for .return
fix .return() mostly [GH# 1106]
remove unneeded empty ctx check in coroutine.invoke back from coro

changed t/pmc/coroutine.t to match the new implementation.
Fixed: 9, 13, 14, 15, 16
Remaining todo:
-  2: wrong returncc cont to label, regression (also syn_7)
- 14: wrong cont
[test] change regressing returncc label from coro to return value
trace: print Coro similar to Sub with -t1
coro: fix dead state with and without autoreset

we do not error when the coro returns from return/returncc.
we rather error when a dead coro is called, new yield state 2.
coro: do not reset cont address
coro: more debug tracing. also track cont pc
coro: fixed return address from dead coro

this fixes the return to label regressions. But there are
still 2 broken cases: 14, 17 with wrong return address when dead is caught
and on autoreset.

remove ctx debugging and add proper pc debugging instead
[cage] fix 1 obscure codingstd test
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