manifest: Track CM's libcore

To make use of patches like this: http://review.cyanogenmod.org/#/c/45251/

Change-Id: I0d10605442f9745ea2d70f396008bdcffced7bea
Signed-off-by: Rohan Mathur <rohanmathur34@gmail.com>
Merge "manifest: Track CM's libcore" into jb-mr1