kernel: use target strip command

Change the strip command used from the hardcoded arm
to the toolchain defined strip.

Change-Id: Id900765e8dc93af1345081f4fd0c52bebcd07fea
Additional overrides

Change-Id: I768e26d2fad021a9eb30decf15e61ba996b673e5
Just a few more for flexibility

Change-Id: I264191a7ff2235d0effe038c39a976a25985f529
Merge branch 'cm-10.2' of https://github.com/CyanogenMod/android_build into cm-10.2