[perl #129353] [NATIVECALL][LTA] The error message of CStruct recommends to use Perl 6 native types

[Tobias Leich via RT]

Fixed with:
https://github.com/MoarVM/MoarVM/commit/688796b434
https://github.com/rakudo/rakudo/commit/a92f092ac5

The error message now reads:

$ perl6 -e 'class Foo is repr<CStruct> { has Buf $.a }'
===SORRY!=== Error while compiling -e
CStruct representation only handles attributes of type:
  (u)int8, (u)int16, (u)int32, (u)int64, (u)long, (u)longlong, num16, num32, 
(s)size_t, bool, Str
  and types with representation: CArray, CPointer, CStruct, CPPStruct and CUnion
at -e:1