Merge: Strip content length in requests with "transparent" gzip handling

Original AOSP/libcore commit from Brian Carlstrom:
We need to strip both the Content-Length and the Content-Encoding
for such requests. In such requests, it will be the length of the
compressed response. We hide the fact that compression is taking place
from clients, so we shouldn't give them the content length either.

Change-Id: I80713ab33143945c5e2656f478d83cc9e60226a8