For printf format string checking, move the tracking of the data argument index out of

For printf format string checking, move the tracking of the data argument index out of
Sema and into analyze_printf::ParseFormatString().  Also use a bitvector to determine
what arguments have been covered (instead of just checking to see if the last argument consumed is the max argument).  This is prep. for support positional arguments (an IEEE extension).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97248 91177308-0d34-0410-b5e6-96231b3b80d8