Bug 18927: Use fully qualified subroutine names in C4::Items

Bug 18927: Use fully qualified subroutine names in C4::Items

rebuild_zebra.pl fails in some conditions (perl version?)
I do not recreate but it has been reported that reindex fails with:
  error retrieving biblio 94540 at /usr/share/koha/bin/migration_tools/rebuild_zebra.pl line 683, <DATA> line 751.

To fix it we can use fully qualified subroutine names for:
  GetMarcFromKohaField
  GetMarcBiblio
  GetBiblionumberFromItemnumber
  TransformKohaToMarc
  GetFrameworkCode

Test plan:
Confirm the rebuild_zebra script still works correctly after this patch

Signed-off-by: Lee Jamison <ldjamison@marywood.edu>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>