rsyslog: add ptest support

Changed:
- add a patch to use serial-tests config needed by ptest
- add a patch to fix rsyslog test cases don't finish issue
- add run-ptest, do_compile_ptest and do_install_ptest
- add dependency for rsyslog-ptest
- add PACKAGECONFIG for valgrind

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>