Update to version 1.1.1. Removed build step because %make throws errors in this version, but %make_install works fine, with the output of comm below showing nothing lost.
comm -3 <(lspisi zstd-1.0.0-3-1-x86_64.eopkg) <(lspisi ~/SolusPackages/zstd/zstd-1.1.1-4-1-x86_64.eopkg) && comm -3 <(lspisi zstd-devel-1.0.0-3-1-x86_64.eopkg ) <(lspisi ~/SolusPackages/zstd/zstd-devel-1.1.1-4-1-x86_64.eopkg)
/usr/lib64/libzstd.so.1.0.0
/usr/lib64/libzstd.so.1.1.1
/usr/include/zstd_errors.h