libc/eglibc: normalize eglibc hidden version names

In the previous patches to glibc and uclibc, we standardized on hidden
version names:

LIBC_<LIBC NAME>_V_<VERSION>

This patch updates EGLIBC to be the same for consistency to:

LIBC_EGLIBC_V_<VERSION>

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>

 COPYING