Stop using `IF` in our Cython code #2675

Job	Run time
Build source distribution	23s
Decide which wheel types to build	1s
Publish docs	0s
macosx_x86_64 wheels	7m 15s
manylinux_x86_64 wheels	4m 9s
macosx_arm64 wheels	7m 21s
musllinux_x86_64 wheels	3m 46s
manylinux_i686 wheels	3m 52s
Build and test wheels	0s
upload_pypi	0s
	26m 47s

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