Specify -msse3 on host as on target.

Make the host and the target x86 build more uniform by using the same machine flags.
Its unlikely Android has ever been built on a machine without SSE3 support.

Bug: 8068608
Change-Id: I19635528b61bf2c6faf02c2e575b1d9bf8025d3a
Update ARMv7-A flags

Use separate file for NEON targets, add TARGET_CPU_VARIANT (in line to AOSP), add Krait flags
Make LLVM not complain about new flags
Use strict-aliasing, O3 and C++11 mode