[DYNAREC] Added preliminary interblocks deferred flags elimination

[ksco]

The first version is probably too conservative, but it gives good results in some benchmarks.

[ptitSeb]

So for each "peekeable" jump, a limited 16 instructions decoding using only pass0 is done at the landing address to check if flags are regenated and so useless to store a defered flag befor ethe jump. Clever reuse of existing code!

[ptitSeb]

I think this break the Wow64 build:

ld.lld: error: undefined symbol: _tls_index
/usr/local/bin/cmake -E rm -f CMakeFiles/wowbox64.dir/objects.a
>>> referenced by objects.a(dynarec_native.c.obj):(interblock_flags_needed)
>>> referenced by objects.a(dynarec_native.c.obj):(interblock_flags_needed)
clang: error: linker command failed with exit code 1 (use -v to see invocation)

On the other hand, I'm not sure it's necessary to have this thread local has dynarec is not supposed to be multithreaded: everything is static and dynablock building is behind a mutex.