printf: add fflush(stdout) at the end

[lakshmih]

Some platforms (Windows in our case) seem to need this.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[bashbaug]

Can you say a bit more why this is required? What are the symptoms before this change, and how does the change fix them?

I know the printf tests do some odd things with stdout, but the tests themselves (specifically, doTest) also have calls to fflush(stdout). Are we missing a call somewhere in doTest? Or, is there some reason why we still need this additional call in the test main function for some reason?

[nikhiljnv]

@lakshmih
Are you seeing behavior similar to #1010 that you are trying to fix with this change?

[lakshmih]

@nikhiljnv Not sure it is the same issue but essentially we don't get output from the print_results function in testHarness.cpp that prints the cumulative pass/fail result without the fflush.
@bashbaug The individual doTest messages do get flushed but it is the final pass / fail from the harness (see above) that is missing.

[svenvh]

we don't get output from the print_results function in testHarness.cpp that prints the cumulative pass/fail result without the fflush.

Perhaps it makes more sense to move the fflush into the harness's print_results function then?