auto::mathl: probe and use more long math functions

Renamed auto::labs to auto::mathl
Use: ceill floorl powl fmodl expl logl in the math ops
Closes GH #1111
floatval=long double: fix fdiv_i_i neg, add fabsl

also fix ceil_n, floor_n for long double.
use ceill and floorl only with long double.

fix most long double tests,
just the embed API is still broken for long double:
t/src/embed/pmc.t                         (Wstat: 256 Tests: 9 Failed: 1)
  Failed test:  2
t/src/extend_vtable.t                     (Wstat: 3840 Tests: 134 Failed: 15)
  Failed tests:  7, 22, 46-47, 59, 72, 80-81, 89-90, 96-97
                103-104, 128

Missing: long variants for more float methods, like sin, cos, ...
Closes GH #1111
[test] todo packfile re-pack with non-default numbers
[test] adjust tests for make test VALGRIND=valgrind

result should not interleave with post-exit valgrind ==pid== output
e.g. => "42==16469== Memcheck, a memory error detector"
We need to add "42\n" because ==... is only filtered at new lines.

Some of the filtered valgrind lines are darwin specific:
--$pid:0:syswrap- WARNING: Ignoring sigreturn( ..., UC_RESET_ALT_STACK );
on longjmp, darwin only.
or UNKNOWN task message [id 3403, to mach_task_self(), reply 0x813]

Closes GH #1150
[test] refactor, new valgrind_filter function

also print LEAK SUMMARY: definitely lost: $1 bytes in $2 blocks
if so. GH #1150
[test] fix GLOB* temp file creation

regression from commit caba76f589a9aa.
mixed up handle and filename, as run_command actually requires
a name and not a handle for STDERR.
[docs] Update stability and memory_internals

stability was written in 2007. Just the deprecation cycle
needed to be updated.

memory_internals talks as if mark&sweep is the only GC.
Improve that.
[test] minor improvements in stress/gc.t and src/extend.t 19
[examples] fix wrong load_bytecode paths
[build] change add_to_generated for .dump files

move from pmc2c.pl to Makefile.
1. generated default.dump also, which was missing most of the time.
2. 3rd party langs may not need MANIFEST.generate files. let them handle it.
[pmc] start with resizablepmcarray unshift optimizations

using a max offset 8, as in nqp/qrpa. See GH #1152
Here offset is still const 0.
[pmc] rpa trace: do_shift(INTERP, ...)

need interp for tracing, slow or fast
[pmc] rpa enabled shift optimizations w/o splice

resizablepmcarray shift,unshift,resize,push,pop look now good.
just splice is missing. GH #1152
[pmc] rpa: trying to fix splice WIP

Not offset optimized yet. And something still fails.
GH #1152
[pmc] rpa: WIP some more fixes, but still failing
[pmc] rpa: remove old code without USE_OFFSET

Still one invalid access of freed data in push_pmc, and
invalid read in shift_pmc.
valgrind ./parrot_old -o runtime/parrot/library/HLL.pbc ext/nqp-rx/src/stage0/HLL-s0.pir
[pmc] rpa: fix 2 cases: shift+push offset overflow

also:
* fix non-debugging TRACE_RPAd macro
* add some UNLIKELY hints
[pmc] rpa: fix defined, no throw. add get/set trace with -t1
[pmc] rpa: specialize sort+reverse, need offset

also add offset to append
add more notes to fixedpmcarray vtable docs
[pmc] rpa: optimize splice shrink fast on offset

if there is enough room at the left to fill in the elements
from from, adjust offset and jump to the fill routine

this optimization is not present in qrpa, and executed e.g.
in data_json.