[foreign] RFR : Fixes to StdLibTest

[Jorn Vernee]

Hello,

Please review this patch which does a few fixes to StdLibTest:

Diff: 
https://gist.github.com/JornVernee/312ecb03d93882efac1f86ccc8ad1f25

This patch fixes 3 things:

1.) 'puts' returns a non-negative value on success [1], but the test was 
testing > 0. I changed it to >= 0, since the MSVC implementation returns 
exactly 0.

2.) Switched the test_time test from testing localtime(), which is 
locale dependent to testing gmtime() which always uses the GMT timezone, 
since the locale dependency was giving trouble in cygwin [2].

3.) Also for the test_time test, I changed the way the test parameters 
are being generated, since it was apparently generating invalid values 
for windows, so the native function was returning null, and the test was 
failing.

Since I'm not a committer someone else will have to create a commit and 
push this.

Thanks,
Jorn

[1] : https://en.cppreference.com/w/c/io/puts
[2] : 
http://mail.openjdk.java.net/pipermail/panama-dev/2018-September/002753.html