Typos in changelog and comments

compiler/deSugar/Desugar.hs

compiler/simplCore/SetLevels.hs

compiler/specialise/SpecConstr.hs

compiler/typecheck/TcInteract.hs

compiler/typecheck/TcTyDecls.hs

configure.ac

libraries/base/Data/Data.hs

libraries/base/GHC/IO/Buffer.hs

libraries/base/changelog.md

testsuite/tests/indexed-types/should_fail/T2239.hs

testsuite/tests/typecheck/should_fail/tcfail179.hs

testsuite/tests/typecheck/should_run/T1735_Help/Basics.hs