Followed the how to guides all compiled sweet :)
LD_LIBRARY_PATH=/opt/glibc-2.14/lib Set
strings libc.so.6 | grep GLIBC
GLIBC_2.2.5
GLIBC_2.2.6
GLIBC_2.3
GLIBC_2.3.2
GLIBC_2.3.3
GLIBC_2.3.4
GLIBC_2.4
GLIBC_2.5
GLIBC_2.6
GLIBC_2.7
GLIBC_2.8
GLIBC_2.9
GLIBC_2.10
GLIBC_2.11
GLIBC_2.12
GLIBC_2.13
GLIBC_2.14
GLIBC_PRIVATE
But doing a Yum update
Error: Package: libzstd-1.3.4-1.el7.x86_64 (mariadb) Requires: libc.so.6(GLIBC_2.14)(64bit)
I have read about changing symbolic link etc but