target-arm, tcg, x86: Preliminary implementation of SIMD to SIMD translation

The ARM NEON SIMD instruction set is now translated into SIMD
micro-operations, which are translated into MMX/SSE instructions by the
tcg on x86 hosts. This is a work in progress, a lot of NEON instructions
are not implemented yet.
Update to master
Use master gen_logicq_cc rather than 1.4 one
comment simd_128_shl_i8 x86 tcg backend
Fix uninitialization compilation error