Fix read issue detected by the following Python program. The issue was that the...

Fix read issue detected by the following Python program.  The issue was that the caller's buffer pointer was not being advanced between segments of the read data.

Signed-off-by: lpleahy
-----  UnbufferedRead.py  -----

import httplib
conn = httplib.HTTPConnection("10.241.97.30")
conn.request('GET', '/')
resp = conn.getresponse(buffering=True)
if resp.status != 200:
   print "status:", resp.status
   print "aborting"
   sys.exit(1)
while True:
   chunk = resp.read()
   if not chunk:
       break
   print chunk

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13077 6f19259b-4bc3-4df7-8a09-765794883524