Do not use the "date" command in the configure.in file, builds not reproductible

Hello,

The way the configure file uses the date command to set the version is making it impossible to have reproducible builds: m4_esyscmd_s([date +%y.%V.$(git rev-list $(git describe --abbrev=0)..HEAD --count) -d "@$(git log -1 --pretty=format:%ct)" || echo 0])

It's common for distribution (debian-like distributions are doing this by default) to re-create the autofoo files at build time, this means that at every build, the version will be different