RFR(xxs): 8224023: Redo the fix for ErrorFile option does not handle pre-existing error files of the same name

[Thomas Stüfe]

Hi all,

may I please have reviews for this small change.

bug: https://bugs.openjdk.java.net/browse/JDK-8224023
cr:
http://cr.openjdk.java.net/~stuefe/webrevs/8224023-redo-errorfile-overrite-fix/webrev.00/webrev/

8221738 changed the overwrite logic for hs-err files (they are now
overwritten, which only affects cases where the file is specified with
-XX:ErrorFile=abc).

Accidentally I also changed the logic for replay files, and for good
measure added a bug, which was a nice feat for a one line patch.

Anyways, here is the new version: We open hs-err files with O_TRUNC, but
replay files with O_EXCL like we did before. Should we at some point decide
we want to apply the same overwrite logic to replay files, we can remove
this coding again.

I manually tested the error handler tests and also all tests under
compiler/ciReplay, no issues.

Thanks, Thomas