Merge branch 'ps/tests-wo-iconv-fixes'

Some tests assumed "iconv" is available without honoring ICONV
prerequisite, which has been corrected.

* ps/tests-wo-iconv-fixes:
  t6006: don't use iconv(1) without ICONV prereq
  t5550: add ICONV prereq to tests that use "$HTTPD_URL/error"
  t4205: improve handling of ICONV prerequisite
  t40xx: don't use iconv(1) without ICONV prereq
  t: don't set ICONV prereq when iconv(1) is missing

diff --cc t/test-lib.sh
Simple merge