PERLLIB, @INC: Use BEGIN { }

PERLLIB, @INC: Use BEGIN { }

unshifting @INC is only effective if done at compile time, so that it
affects `use' directives.  So "Perl: Put . on @INC"
f261b07cbe96844dba5d8594c38149c0b179068a is simply broken

This patch was autogenerated using the following rune:

  git-grep -l 'unshift @INC' | xargs perl -i~ -pe 's#\bunshift\s+\@INC,\s*qw\(\.\)\;#BEGIN { $& }#'

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>