Revert fix for “Preloading a replacement uname is causing environment
to be cleaned if libpthread is loaded”. UTS namespaces should now
offer a cleaner way yo do this.
First phase of sendmsg/recvmsg/sendmmsg/recvmmsg ABI revert:
GLIBC_2.24 compatibility symbols.
This should allow us to run old binaries (with the GLIBC_2.24 symbols)
while rebuild packages to use the old ABI again.