# get the current perl version as a string:
my $pversion = join(".",map{ord()}split //,$^V);

# find paths in @INC that contain or end in that string:
my %inc;
my $build;
for (sort grep m!/\Q$pversion\E(?:/|$)!, @INC) {
    if ( m!/$pversion$! ) {
        $inc{$_} = 0;
    }
    elsif ( m!(.*?$pversion)/([^/]+)$! ) {
        $inc{$1} = 1;
        $build ||= $2;
    }
}
for ( keys %inc ) {
    if ( $inc{$_} == 0 and -d "$_/$build" ) {
        warn "adding $_/$build to INC array\n";
        push @INC, "$_/$build";
    }
}
# now we can "require" modules that have build-specific components
# in paths that have just been added.