RFR(S): 8154921: Fix aix after "8146879: Add option for handling existing log files in UL"

[Lindenmaier, Goetz]

Hi

8146879 breaks the build on AIX, as stdio.h defines a macro fileno.
I renamed os::fileno() to os::get_fileno().

Please review this small fix. I please need a sponsor.
http://cr.openjdk.java.net/~goetz/wr16/8154921-aix_fileno/webrev.01/

Best regards,
  Goetz.