Cleanup useless/non-constexpr branchs #2430

Job	Run time
externals (clang, x86, -msse2)	46m 14s
externals (gcc, x86, -msse2)	48m 16s
arm (clang, aarch64, -Wno-psabi)	48m 17s
macosx (clang, x86_osx, -mavx)	48m 25s
arm (clang, arm, -Wno-psabi)	48m 17s
nosimd (clang, x86, -DEVE_NO_SIMD)	38m 33s
nosimd (gcc, x86, -DEVE_NO_SIMD)	47m 58s
riscv (clang, riscv, -mrvv-vector-bits=128)	34m 47s
x86-clang (clang, x86, -msse4.2)	13m 51s
no_pch (clang, x86, -msse2)	48m 15s
x86-clang (clang, x86, -mavx)	17m 12s
no_pch (gcc, x86, -msse2)	48m 14s
x86-clang (clang, x86, -mavx2)	16m 35s
other-arch	0s
x86-gcc	0s
avx512	1s
other-cases	1s
	8h 24m 56s

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