Created attachment 652804 [details]
attached is the output snippet of the error
Created attachment 652806 [details]
I have the same issue on my UP1100.
At line 152 in programs/util.c of zstd-1.4.5, it is determined whether macro PLATFORM_POSIX_VERSION is 200809L or more and whether struct stat has member st_mtim by whether macro st_mtime is defined.
If __USE_XOPEN2K8 is defined and built with gcc version 3.3 or higher, Alpha architecture does not define macro st_mtime by adding both members st_mtim and st_mtime to struct stat by using union.(/usr/include/bits/stat.h)
In programs/platform.h, macro PLATFORM_POSIX_VERSION is defined equal to _POSIX_VERSION. Since __USE_XOPEN2K8 is defined in /usr/include/features.h, _POSIX_VERSION is 200809L in /usr/include/unistd.h. On Linux/alpha with __USE_XOPEN2K8 defined (in /usr/include/features.h), I think it can be said that struct stat will include member st_mtim even if macro st_mtime is not defined.
A simple solution is to treat Linux/alpha specially, but if there is a good way to easily determine if a structure contains a member, I'd prefer it.
I was able to build with a attached patch that allows Linux/alpha if PLATFORM_POSIX_VERSION is 200809L or higher.
Created attachment 656624 [details, diff]
patch for alpha architecture