Make --ll-exception output use OS-dependant path separators consistently

[p6rt]

Migrated from rt.perl.org#130226 (status was 'new')

Searchable as RT130226$

[p6rt]

From winexpertu@yandex.ru

Currently there is no much consistency at all, example of it on Windows using Rakudo version 2016.11 built on MoarVM version 2016.11 implementing Perl 6.c.​:

perl6 --ll-exception test.pl6

No such method 'find_private_method' for invocant of type 'Perl6​::Metamodel​::PackageHOW'
  at SETTING​::src/core/Exception.pm​:64 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:throw)
from SETTING​::src/core/Exception.pm​:2431 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:)
from gen/moar/m-BOOTSTRAP.nqp​:3217 (C​:\rakudo/share/nqp/lib/Perl6/BOOTSTRAP.moarvm​:)
from SETTING​::src/core/Mu.pm​:686 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:dispatch​:<!>)
from I​:\Developer\Perl\7DtD_Modding\P6\lib\Attribute\Handling.pm6 (Attribute​::Handling)​:48 (I​:\Developer\Perl\7DtD_Modding\P6\lib\.precomp\4F2986EC86EC577C7E9279547564C2E1A9E9E5A9.1479593101.31865\A4\A4912DE00FF08B2279134C8946591594E45F2023​:handler)
from SETTING​::src/core/Mu.pm​:669 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:dispatch​:<var>)
from I​:\Developer\Perl\7DtD_Modding\P6\lib\Attribute\Handling.pm6 (Attribute​::Handling)​:15 (I​:\Developer\Perl\7DtD_Modding\P6\lib\.precomp\4F2986EC86EC577C7E9279547564C2E1A9E9E5A9.1479593101.31865\A4\A4912DE00FF08B2279134C8946591594E45F2023​:)
from SETTING​::src/core/Any-iterable-methods.pm​:650 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:)
from SETTING​::src/core/Any-iterable-methods.pm​:631 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:sink-all)
from SETTING​::src/core/Seq.pm​:159 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:sink)
from I​:\Developer\Perl\7DtD_Modding\P6\lib\Attribute\Handling.pm6 (Attribute​::Handling)​:8 (I​:\Developer\Perl\7DtD_Modding\P6\lib\.precomp\4F2986EC86EC577C7E9279547564C2E1A9E9E5A9.1479593101.31865\A4\A4912DE00FF08B2279134C8946591594E45F2023​:tweak)
from SETTING​::src/core/Mu.pm​:135 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:BUILDALL)
from SETTING​::src/core/Mu.pm​:111 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:BUILDALL)
from SETTING​::src/core/Mu.pm​:107 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:bless)
from SETTING​::src/core/Mu.pm​:94 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:new)
from SETTING​::src/core/Mu.pm​:92 (C​:\rakudo/share/perl6/runtime/CORE.setting.moarvm​:new)
from test.pl6​:27 (<ephemeral file>​:<unit>)
from test.pl6​:1 (<ephemeral file>​:<unit-outer>)
from gen\moar\stage2\NQPHLL.nqp​:1437 (C​:\rakudo\share\nqp\lib/NQPHLL.moarvm​:eval)
from gen\moar\stage2\NQPHLL.nqp​:1640 (C​:\rakudo\share\nqp\lib/NQPHLL.moarvm​:evalfiles)
from gen\moar\stage2\NQPHLL.nqp​:1534 (C​:\rakudo\share\nqp\lib/NQPHLL.moarvm​:command_eval)
from src/Perl6/Compiler.nqp​:27 (C​:\rakudo\share\nqp\lib/Perl6/Compiler.moarvm​:command_eval)
from gen\moar\stage2\NQPHLL.nqp​:1508 (C​:\rakudo\share\nqp\lib/NQPHLL.moarvm​:command_line)
from gen/moar/m-main.nqp​:46 (C​:\rakudo\share\perl6\runtime\perl6.moarvm​:MAIN)
from gen/moar/m-main.nqp​:37 (C​:\rakudo\share\perl6\runtime\perl6.moarvm​:<mainline>)
from <unknown>​:1 (C​:\rakudo\share\perl6\runtime\perl6.moarvm​:<main>)
from <unknown>​:1 (C​:\rakudo\share\perl6\runtime\perl6.moarvm​:<entry>)