fix pmt processing

fix pmt processing
there were 2 problems
1. when the program list in the pat contains a network PID, the pmt parsing
   code doesn't properly skip this entry. this causes attempts to interpret
   a pat as a pmt since the pid entry in the table is left initialized to 0.
2. pmt parsing always waits till the start of the second pmt section before
   parsing the first. if for some reason there were only one pmt in the
   stream, it would never parse the pmt. I've changed it to parse the pmt
   as soon as all the necessary bytes are collected.

git-svn-id: svn://localhost/HandBrake/trunk@1916 b64f7644-9d1e-0410-96f1-a4d463321fa5