Remove auth-options support from initdb

Remove auth-options support from initdb

When --auth was added to initdb in commit e7029b212755 it had support
for auth options separated by space from the auth type, like:

    --auth pam <servicename>
    --auth ident sameuser

Passing an option to the ident auth type was removed in 01c1a12a5bb4
which left the pam auth-options support in place. 8a02339e9ba3 broke
this by inverting a calculation in the strncmp arguments, which went
unnoticed for a long time.  The ability to pass options to the auth
type was never documented.

Rather than fixing the support for an undocumented feature which has
been broken for all supported versions, and which only supports one
out of many auth types which can take options, it is removed.

Reported-by: Jingxian Li <[email protected]>
Reviewed-by: Michael Paquier <[email protected]>
Reviewed-by: Aleksander Alekseev <[email protected]>
Discussion: https://postgr.es/m/[email protected]