Certain uClibc versions declare b64_ntop but do not actually implement it, this leads to conflicting declarations
when the tmux compat replacement function is used. Rename the replacement to local_b64_ntop and define b64_ntop
to local_b64_ntop if the libc indeed implements it.
git-svn-id: svn://svn.openwrt.org/openwrt/packages@30355 3c298f89-4303-0410-b956-a3cf2f4a3e73