Allow bypassing runtime feature check of TZCNT instructions.

[mtl1979]

• This avoids conditional branch when it's known at build time that TZCNT instructions are always supported

See discussion in comments of 9bd28d9

[codecov]

Codecov Report

Merging #1186 (f6cc79f) into develop (a5a9844) will decrease coverage by 0.42%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #1186      +/-   ##
===========================================
- Coverage    87.96%   87.54%   -0.43%     
===========================================
  Files          108      112       +4     
  Lines         9283     9601     +318     
  Branches      2310     2422     +112     
===========================================
+ Hits          8166     8405     +239     
- Misses         921      953      +32     
- Partials       196      243      +47     

Flag	Coverage Δ
macos_clang	27.58% <ø> (ø)
macos_gcc	71.04% <ø> (ø)
ubuntu_clang	86.06% <ø> (+0.02%)	⬆️
ubuntu_clang_debug	85.86% <ø> (+0.02%)	⬆️
ubuntu_clang_inflate_allow_invalid_dist	85.27% <ø> (-0.62%)	⬇️
ubuntu_clang_inflate_strict	85.36% <ø> (-0.62%)	⬇️
ubuntu_clang_mmap	86.12% <ø> (+0.67%)	⬆️
ubuntu_clang_pigz	39.71% <ø> (ø)
ubuntu_clang_pigz_no_optim	39.97% <ø> (ø)
ubuntu_clang_pigz_no_threads	39.29% <ø> (ø)
ubuntu_clang_reduced_mem	86.25% <ø> (+0.67%)	⬆️
ubuntu_gcc	72.52% <ø> (-0.53%)	⬇️
ubuntu_gcc_aarch64	72.70% <ø> (ø)
ubuntu_gcc_aarch64_compat_no_opt	70.10% <ø> (ø)
ubuntu_gcc_aarch64_no_acle	70.98% <ø> (ø)
ubuntu_gcc_aarch64_no_neon	70.94% <ø> (ø)
ubuntu_gcc_armhf	72.69% <ø> (ø)
ubuntu_gcc_armhf_compat_no_opt	70.01% <ø> (ø)
ubuntu_gcc_armhf_no_acle	72.71% <ø> (ø)
ubuntu_gcc_armhf_no_neon	72.65% <ø> (ø)
ubuntu_gcc_armsf	72.69% <ø> (ø)
ubuntu_gcc_armsf_compat_no_opt	70.01% <ø> (ø)
ubuntu_gcc_benchmark	74.62% <ø> (+0.04%)	⬆️
ubuntu_gcc_compat_no_opt	71.98% <ø> (ø)
ubuntu_gcc_compat_sprefix	74.02% <ø> (+0.04%)	⬆️
ubuntu_gcc_mingw_i686	?
ubuntu_gcc_mingw_x86_64	0.00% <ø> (ø)
ubuntu_gcc_no_avx2	71.78% <ø> (+0.35%)	⬆️
ubuntu_gcc_no_ctz	73.91% <ø> (ø)
ubuntu_gcc_no_ctzll	73.67% <ø> (ø)
ubuntu_gcc_no_pclmulqdq	70.73% <ø> (+0.03%)	⬆️
ubuntu_gcc_no_sse2	71.17% <ø> (-0.39%)	⬇️
ubuntu_gcc_no_sse4	71.53% <ø> (+0.41%)	⬆️
ubuntu_gcc_o3	74.00% <ø> (ø)
ubuntu_gcc_osb	∅ <ø> (∅)
ubuntu_gcc_pigz	37.72% <ø> (-0.09%)	⬇️
ubuntu_gcc_pigz_aarch64	38.30% <ø> (+0.02%)	⬆️
ubuntu_gcc_ppc	73.39% <ø> (ø)
ubuntu_gcc_ppc64	74.15% <ø> (ø)
ubuntu_gcc_ppc64le	73.34% <ø> (ø)
ubuntu_gcc_ppc_no_power8	74.39% <ø> (ø)
ubuntu_gcc_s390x	74.40% <ø> (ø)
ubuntu_gcc_s390x_dfltcc	73.10% <ø> (?)
ubuntu_gcc_s390x_dfltcc_compat	70.78% <ø> (?)
ubuntu_gcc_s390x_no_crc32	74.16% <ø> (ø)
ubuntu_gcc_sparc64	74.29% <ø> (ø)
ubuntu_gcc_sprefix	73.83% <ø> (+0.04%)	⬆️
win64_gcc	73.00% <ø> (ø)
win64_gcc_compat_no_opt	72.73% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
fallback_builtins.h	100.00% <ø> (ø)
inflate_p.h	97.14% <0.00%> (-2.86%)	⬇️
deflate.c	82.49% <0.00%> (-0.44%)	⬇️
gzlib.c	69.33% <0.00%> (ø)
uncompr.c	90.90% <0.00%> (ø)
arch/s390/dfltcc_deflate.c	70.58% <0.00%> (ø)
arch/s390/dfltcc_common.c	84.84% <0.00%> (ø)
arch/s390/dfltcc_detail.h	54.90% <0.00%> (ø)
arch/s390/dfltcc_inflate.c	88.88% <0.00%> (ø)
inflate.c	94.43% <0.00%> (+0.01%)	⬆️
... and 2 more

---

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[nmoinvaz]

Need to add this flag to README.md.

[nmoinvaz]

We are also missing FORCE_SSE2 in the README.md (but the configure flag is there). If you add FORCE_SSE2 to readme I think it would be okay as separate commit.

[mtl1979]

Need to add this flag to README.md.

Added... I was delaying non-code additions due to long backlog on GitHub actions...