[Z80] Optimize shift right by (bitwidth-1) to inline sequences #77

Job	Run time
build-llvm (macos-15-intel, Release)	10m 53s
build-llvm (ubuntu-22.04, Release)	5m 25s
build-llvm (macos-14, Release)	6m 27s
build-llvm (ubuntu-latest, Release)	5m 9s
build-clang (ubuntu-latest, Release)	3m 55s
build-clang (macos-15-intel, Release)	8m 25s
build-clang (macos-14, Release)	3m 38s
test-llvm-z80 (ubuntu-22.04, Release)	1m 29s
test-llvm-z80 (macos-15-intel, Release)	2m 4s
test-llvm-z80 (ubuntu-latest, Release)	1m 38s
test-llvm-z80 (macos-14, Release)	1m 42s
build-clang (ubuntu-22.04, Release)	3m 57s
test-llvm	0s
test-clang	0s
nightly	0s
	54m 42s

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