default file for doLock and doUnlock

Hi all:

The attached patch makes the YumBase.doLock and doUnlock
methods use 
YUM_PID_FILE as the lock file if no lock file name is
provided. This way 
if callers don't want to do anything tricky, they don't have
to know 
about the file's location, or provide it.

-James
_______________________________________________
Yum-devel mailing list
Yum-devellinux.duke.edu
https://lists.dulug.duke.edu/mailman/listinfo/yum-devel