Fix various cpu detection issues

Update htscodecs submodule and add checks for cpuid symbols

Adds cpuid configure checks to HTSlib, along with adjustments to the Makefile and hts_probe_cc.sh for people who like to run "make" without "./configure". For both, if the cpuid check fails, the SSE and AVX tests will be skipped as the features they test for would not be used even if the corresponding code is built.

Companion to samtools/htscodecs#116
Improve tests for avx512 intrinsics

Some compiler installations (notably xcode for MacOS El Capitan) are missing some of the avx512f intrinsics. As these were not specifically checked for in configure, it enabled avx512 but builds failed due to the missing symbols. Fix by adding some extra lines to the avx512f configure test so it can turn avx512 off on these platforms.

Companion to samtools/htscodecs#118; fixes #1773
Fixes build failures on some old clang versions following merge of #1764

Builds on clang 3.7 and 3.8, and Xcode for MacOS El Capitan, died because __builtin_cpu_supports("ssse3") reports an error "invalid cpu feature string for builtin". To prevent this, add a configure check to verify that it works, and disable the optimised code if it doesn't. Note that no equivalent is added for make-only builds, as these are very old compilers and it seems not unreasonable to have to run configure in order to use them.

samtools / htslib