swift234

[stdlib] Remove incorrect format specifier checks

String.init(format:locale:arguments:) contained a check to make sure
that the format string didn't try to format more arguments than were
actually passed.  However, the check didn't guarantee safety (since the
format specifiers didn't have to match the *type* of the passed
argument) and contained bugs such as
https://bugs.swift.org/browse/SR-1378.  Since the check was not a
guarantor of safety and was wrong, it is hereby removed.

If checks are to be reintroduced, they should both be correct and
guarantee complete safety.  Doing this check correctly is a nontrivial
job (the code in Clang to parse such specifiers is well over 500 lines),
and should be taken on as a distinct project.