SUNRPC: Clean up RPCBIND_MAXUADDRLEN definitions
SUNRPC: Clean up RPCBIND_MAXUADDRLEN definitions

Clean up: Replace the single-integer definition of RPCBIND_MAXUADDRLEN
with a definition that is based on previously defined address string
sizes, and document the way this maximum is calculated.  Also provide
a separate macro for the size of the port number extension.

Signed-off-by: Chuck Lever <e7d8216bf9b1956703857d0050bd04192118f43d@oracle.com>
Signed-off-by: Trond Myklebust <6a1f9db795c9fc44be97d66ab114c53193bd3d13@netapp.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas