Remove unused positional argument for printf

The format string for hints only prints the second argument (string) and drops
the first argument (hint id). Depending on how you read the POSIX text for
printf, this could be valid. But for practical reason, i.e., unpacking the
va_list passed to printf based on the formating information, it makes sense
to fix the implementation and not pass the id for hint.

Failing testcases were:

misc_bugs/teams-reduction.c
ompt/parallel/not_enough_threads.c

Differential Revision: https://reviews.llvm.org/D41504

llvm-svn: 321361