shim 15.3 release candidate 4

Hopefully the last release candidate.  Here's the shortlog since rc3:

Chris Coulson (1):
      Fix boot failures due to variable size constraints

Peter Jones (4):
      Make 'make test' work on gcc 4.8.5
      Don't set LIBDIR in CI builds any more.
      Fix cross-compilation from x86_64->i686
      Try multi-arch CI building using cross compilation
-----BEGIN PGP SIGNATURE-----
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=hyRQ
-----END PGP SIGNATURE-----