[perl #121527] rakudo-moar doen't roundtrip big integer literals

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# New Ticket Created by  Moritz Lenz 
# Please include the string:  [perl #121527]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=121527 >


<moritz> r: say 301281685344656669
<camelia> rakudo-parrot 3699aa, rakudo-jvm 3699aa:
          OUTPUT«301281685344656669␤»
<camelia> ..rakudo-moar 3699aa: OUTPUT«301281685344656640␤»

This causes at least a test failure in t/spec/S32-num/rat.t (test label
Rat.Rat yields correct Rat).