Log Message:
libdeflate: updated to 1.21

Version 1.21

* Fixed build error on x86 with gcc 8.1 and gcc 8.2.
* Fixed build error on x86 when gcc 11 is paired with a binutils version that
  doesn't support AVX-VNNI, e.g. as it is on RHEL 9.
* Fixed build error on arm64 with gcc 6.
* Fixed build error on arm64 with gcc 13.1 and later with some -mcpu options.
* Enabled detection of dotprod support in Windows ARM64 builds.