logging: ensure ANSI color escape is sent in same line/before newline

This fixes multi-line color clobbering in logging daemons like
systemd-journald, which work with single-lines only.

Change-Id: Ia7de9d88aa5ac48ec0d5c1a931a89d21c02c5433
Closes: OS#6249
diff --git a/tests/loggingrb/logging_test.err b/tests/loggingrb/logging_test.err
index b59d2e8..e070561 100644
--- a/tests/loggingrb/logging_test.err
+++ b/tests/loggingrb/logging_test.err
@@ -1,3 +1,2 @@
-You should see this
-You should see this
-
\ No newline at end of file
+You should see this
+You should see this