Update Falcon & McEliece (adding AVX)

[baentsch]

Could fix #896 and #917

Please review initial commit to see changes that led to full PR (running copy_from_upstream)

[baentsch]

@jschanck, @dstebila As the code is now building (improving on #896 (comment) ) would you have time/interest to take a look as to what's happening here with address-sanitizer in (newly added) McEliece-AVX code ?

@bhess Are you OK with the changes done to copy_from_upstream (in d0fc088)

Anyone, maybe @xvzcf (as I have no experience whatsoever with this): Any idea what this is?

/usr/bin/ld: src/kem/classic_mceliece/CMakeFiles/classic_mceliece_348864_avx.dir/pqclean_mceliece348864_avx/transpose_64x256_sp_asm.S.o: relocation R_X86_64_PC32 against symbol `PQCLEAN_MCELIECE348864_AVX_MASK5_0' can not be used when making a shared object; recompile with -fPIC

[bhess]

@bhess Are you OK with the changes done to copy_from_upstream (in d0fc088)

Looks good.

[dstebila]

@jschanck, @dstebila As the code is now building (improving on #896 (comment) ) would you have time/interest to take a look as to what's happening here with address-sanitizer in (newly added) McEliece-AVX code ?

It seems like one of the keywords used in this file is a language extension, which clang with -Wpendatic doesn't like.

One fix is to add the following to .CMake/compiler_opts.cmake in the AddressSanitizer section:

add_compile_options(-Wno-language-extension-token)

I verified locally that the CircleCI AddressSanitizer workflow passes with that option.

[dstebila]

Oh, don't forget to update the algorithm data sheets in the docs folder.