begin_time_lexical_fixup for constants
begin_time_lexical_fixup for constants

This patch applies the fix that jnthn created for BEGIN and CHECK
blocks to constant assignments (which are also run at compile
time). The problem is constant values may have inner blocks that get
serialized and used at runtime. This fix needs to be applied for them
to work, otherwise these explode when exported and used:

constant $const is export = sub { uc "win" };
constant @const is export  = map { uc $_ }, <foo bar baz>;
constant $regex is export  = /{ say "win"} ./;

With something like: Cannot invoke this object (REPR: Null; VMNull)

Fixes RT #127858, #131705

Gnouc/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,tony-o/rakudo,labster/rakudo,tbrowder/rakudo,softmoth/rakudo,labster/rakudo,tony-o/rakudo,usev6/rakudo,tony-o/rakudo,nbrown/rakudo,raydiak/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,tony-o/rakudo,nbrown/rakudo,MasterDuke17/rakudo,jonathanstowe/rakudo,lucasbuchala/rakudo,usev6/rakudo,rakudo/rakudo,nbrown/rakudo,salortiz/rakudo,rakudo/rakudo,awwaiid/rakudo,sjn/rakudo,MasterDuke17/rakudo,sjn/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,salortiz/rakudo,raydiak/rakudo,labster/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,awwaiid/rakudo,raydiak/rakudo,labster/rakudo,usev6/rakudo,Gnouc/rakudo,tbrowder/rakudo,rakudo/rakudo,usev6/rakudo,nbrown/rakudo,salortiz/rakudo,salortiz/rakudo,rakudo/rakudo,labster/rakudo,softmoth/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,rakudo/rakudo,Gnouc/rakudo,jonathanstowe/rakudo,sjn/rakudo,jonathanstowe/rakudo,softmoth/rakudo,sjn/rakudo,tony-o/rakudo,usev6/rakudo,tbrowder/rakudo,nbrown/rakudo,sjn/rakudo,salortiz/rakudo,raydiak/rakudo,nbrown/rakudo,tbrowder/rakudo,salortiz/rakudo,lucasbuchala/rakudo,lucasbuchala/rakudo,tony-o/rakudo,MasterDuke17/rakudo,lucasbuchala/rakudo,softmoth/rakudo,awwaiid/rakudo,awwaiid/rakudo,awwaiid/rakudo,softmoth/rakudo