Update okhttp to the latest version.

This is the version on okhttp master
commit 21e9c8398867f983e8c3cf29c6382690c1e4785d

Change-Id: I4332ee63741c8784eb00b63d636780ae3408b1e9
Merge "Update okhttp to the latest version."
Upgrade to the latest OkHttp.

Note the internal package name has changed from libcore.net.http
to com.squareup.okhttp.

Change-Id: Ib0eb4bdd69f24f2a255975460bd001e59657ddcc
Merge "Upgrade to the latest OkHttp."
Upgrade to the latest OkHttp, with changes through 2013-Feb-01.

This is OkHttp commit 2137b7a72518cfac088757ef6d0fb3d085bf6e3d
Most notable changes are improvements to ConnectionPool (fixing
infinite loops!) and upgrading to SPDY/3.

Change-Id: Icd9e5e3857a45f9b68a164b920d33f48cdddb780
Merge "Upgrade to the latest OkHttp, with changes through 2013-Feb-01."
Update okhttp through to Feb 20.

This is commit 4b7e0b733fe7597bd58014311cbed8592ca313ac
on branch master at

https://github.com/square/okhttp

Change-Id: I68c40a8a0c7518933b6ac124c886d21f4823a809
Merge "Update okhttp through to Feb 20."
Merge tag 'android-4.3_r2.1' into jellybean-mr2.1

Android 4.3 release 2.1