[foreign-jextract] RFR: Fix several failing jdk_jextract tests on Windows

[Jorn Vernee]

Hi,

This patch fixes several failing jdk_jextract tests on Windows.

WRT Test8244959, this was failing because the default library was being used, and a wrong version of sprintf was being
found, causing a failure. I've replaced this call with a custom my_sprintf, that calls vsprintf instead, which gets the
test passing (along with some other long -> long long changes).

There was also a test that was not being run, because the jtreg tag was referencing a different test class. Since the
test that was actually referenced was failing, this caused 2 identical failures. I've changed the jtreg tag to point to
the right class.

Thanks,
Jorn

-------------

Commit messages:
 - Add trailing newline
 - Fix several failing tests on Windows.

Changes: https://git.openjdk.java.net/panama-foreign/pull/226/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/226/webrev.00
  Stats: 73 lines in 6 files changed: 64 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/226.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/226/head:pull/226

PR: https://git.openjdk.java.net/panama-foreign/pull/226