is gnulib needed

[williamcroberts]

gnulib is a posix compliant api wrapper for common functions when your not using glibc. Since we're running linux distros with glibc, do we need it?

[diabonas]

I think this is still there from tpm2-software/tpm2-tss#1177, see tpm2-software/tpm2-tss#1215. Since tpm2-software/tpm2-tss#1254 removed the dependency on Gnulib, we don't need it in the Dockerfile any more.