test: mark flaky tests on smartos

PR-URL: https://github.com/nodejs/node/pull/43596
Refs: https://github.com/nodejs/node/issues/43457
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

test/node-api/node-api.status

@@ -7,3 +7,8 @@ prefix node-api
 [true] # This section applies to all platforms
 
 [$system==win32]
+
+[$system==solaris] # Also applies to SmartOS
+# https://github.com/nodejs/node/issues/43457
+test_fatal/test_threads: PASS,FLAKY
+test_fatal/test_threads_report: PASS,FLAKY