TcSimplify: Condense MASSERT2() usage onto a single line
TcSimplify: Condense MASSERT2() usage onto a single line

Sadly macOS's C preprocessor gets angry at the sight of multi-line macro
invocations.

sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc