Fix Encode(3p) loading module from incorrect relative path

Fix Encode(3p) loading module from incorrect relative path

This is upstream commit
https://github.com/Perl/perl5/commit/c1a937fef07c061600a0078f4cb53fe9c2136bb9

Quoting upstream:

    Without this fix, Encode::ConfigLocal can be loaded from a path
    relative to the current directory, because the || operator will
    evaluate @inc in scalar context, putting an integer as the only
    value in @inc.

Addresses CVE-2021-36770