The PIDs on log lines were supposed to be colorized before, but the
escape sequence was incorrect.  With this change, the code uses the
correct sequence to colorize those PIDs.  E.g., instead of `\033[334m`
(incorrect), use `\033[34m` (correct).

This makes the log messages easier to read.  It also reduces the chance
that a buggy terminal will choke on the invalid escape sequence.

gstreamer/gstreamer#624

Part-of: <gstreamer/gstreamer!689>