Add external/smali and dependencies

Change-Id: I1c177674e06aee8e530d774651d435bb4f64bdd4
Update to prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.11-4.8

Change-Id: Icf8da3f0aac63e45794557903d8bcb6552979570
Add prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.8 for assembler_thumb_test

Change-Id: Ied4a8ed132c8c395679aa1fc5fd33381bcd49c4f