Support pattern matching on empty types #74

Job	Run time
ormolu	5s
build ucm (ubuntu-20.04)	3m 34s
build ucm (macOS-12)	9m 38s
build ucm (windows-2019)	8m 44s
generate jit source	10s
run interpreter tests (ubuntu-20.04)	1m 5s
run transcripts (ubuntu-20.04)	3m 53s
run interpreter tests (macOS-12)	2m 0s
run transcripts (macOS-12)	6m 56s
run transcripts (windows-2019)	6m 33s
build jit binary / build jit binary (ubuntu-20.04)	10s
build jit binary / build jit binary (macOS-12)	20s
build jit binary / build jit binary (windows-2019)	19s
test jit / test jit (ubuntu-20.04)	7s
test jit / test jit (macOS-12)	15s
	43m 49s

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