You should check the cpu version of abi and change geckoview_library and geckoview_asset according to abi.
http://ftp.mozilla.org/pub/mozilla.org/mobile/nightly/
From the link you can download several types of geckoview library.
This is a sample.
[DIR] latest-mozilla-central-android-armv6/ 12-Dec-2013 11:50 -
[DIR] latest-mozilla-central-android-r7/ 12-Dec-2013 11:56 -
[DIR] latest-mozilla-central-android-x86/ 12-Dec-2013 11:56 -
[DIR] latest-mozilla-central-android/ 12-Dec-2013 11:56 -
geckoview_library geckoview_asset.