Ensure that mid-section `align 16` makes PC constant #878

Job	Run time
macos-static (macos-12)	2m 38s
windows (32, windows-2019)	4m 36s
windows (32, windows-2022)	4m 17s
windows (64, windows-2019)	4m 0s
windows (64, windows-2022)	3m 26s
windows-mingw-build (32)	52s
unix (ubuntu-20.04, g++, make)	1m 34s
windows-mingw-build (64)	41s
unix (ubuntu-20.04, g++, cmake)	1m 36s
unix (ubuntu-20.04, clang++, make)	1m 39s
unix (ubuntu-20.04, clang++, cmake)	1m 37s
unix (ubuntu-22.04, g++, make)	3m 6s
unix (ubuntu-22.04, g++, cmake)	2m 45s
unix (ubuntu-22.04, clang++, make)	1m 44s
unix (ubuntu-22.04, clang++, cmake)	1m 45s
unix (macos-11, clang++, make)	7m 22s
unix (macos-11, clang++, cmake)	6m 44s
unix (macos-12, clang++, make)	10m 52s
unix (macos-12, clang++, cmake)	6m 58s
windows-mingw-testing (windows-2019, 32)	3m 14s
windows-mingw-testing (windows-2019, 64)	3m 15s
windows-mingw-testing (windows-2022, 32)	3m 12s
windows-mingw-testing (windows-2022, 64)	3m 27s
	1h 21m 20s

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