NEON code does not build on armv7

[clausecker]

The NEON code in your project appears to use intrinsics that only exist on AArch64. However, you merely check for the presence of NEON extensions, also trying to build this code on AArch32 (aka arm, armv7). Please check this and either remove the intrinsics in question or change the code so it is only build on AArch64. Here are the offending intrinsics I found in my first pass (both in StringView.cpp):

vshrn_high_n_u16
vaddvq_u8

[mosra]

Should be fixed in 0169e21, sorry it took such a massive amount of time.

I also grabbed your patches from the commit referenced above and pushed them as d99afc1 and be614b9 -- thank you for these! I attempted to do some blind polishing but currently have no automated way to check that they work, so hopefully I didn't break anything. Let me know if I did, I'll try to be more responsive this time.

(Tangential, ideally I'd have some sort of a FreeBSD CI build (and a Big-Endian build, and something where I can test 32-bit ARM...), but CircleCI doesn't support those, and my attempts to build those in a VM failed spectacularly: #166)

[clausecker]

Thank you for the update! @yurivict is the one maintaining the port and will probably update it once you release a new version. I'll see if I can get your changes test-built on armv7 in the next days.