arch/arm/boot/compressed/Makefile: CPU arch optimizations

This fixes build errors too when nebula kernel is compiled
together with ROM source using GCC 4.7.4+
nebula: bump to v3.11b

Testing optimation flags
Makefile: optimization flags

 Kernel flags are taken from optimization commit by JustArchi

 https://github.com/JustArchi/android_build/commit/8e1b82c082a8de9160e6c0fc3ded37b591c3e517