tools: Remove buffering for test .log and .trs files

These files are useful to see when a unit test has hung, and where
it has hung. When buffered, they typically remain at zero length
until the test process exits. It's far more useful to inspect
these during the hang.

Closes cockpit-project#9603

tools/tap-driver

@@ -76,9 +76,9 @@ class Driver:
     def __init__(self, args):
         self.argv = args.command
         self.test_name = args.test_name
-        self.log = open(args.log_file, "wb")
+        self.log = open(args.log_file, "wb", 0)
         self.log.write(("# %s\n" % " ".join(sys.argv)).encode("UTF-8"))
-        self.trs = open(args.trs_file, "w")
+        self.trs = open(args.trs_file, "w", 1)
         self.color_tests = args.color_tests
         self.expect_failure = args.expect_failure
         self.width = terminal_width() - 9