Modified error output and new tests for PolyKinds commit

tests/arrows/should_fail/T5380.stderr

tests/gadt/rw.stderr

tests/ghci/scripts/Defer02.stderr

tests/ghci/scripts/Defer02.stdout

tests/indexed-types/should_compile/Simple14.stderr

tests/indexed-types/should_compile/T3208b.stderr

tests/indexed-types/should_compile/all.T

tests/indexed-types/should_fail/GADTwrong1.stderr

tests/indexed-types/should_fail/NoMatchErr.stderr

tests/indexed-types/should_fail/SimpleFail15.stderr

tests/indexed-types/should_fail/SimpleFail5a.stderr

tests/indexed-types/should_fail/SimpleFail6.stderr

tests/indexed-types/should_fail/SkolemOccursLoop.hs

tests/indexed-types/should_fail/SkolemOccursLoop.stderr

tests/indexed-types/should_fail/T1900.stderr

tests/indexed-types/should_fail/T3330a.stderr

tests/indexed-types/should_fail/T3440.stderr

tests/indexed-types/should_fail/T4093a.stderr

tests/indexed-types/should_fail/T4093b.stderr

tests/indexed-types/should_fail/T4179.stderr