lightrec: Added functions lightrec_free_block and lightrec_destroy
lightrec: Require a memory map to be passed to lightrec_init
lightrec: Update prototype of function lightrec_recompile_block

It now takes a PC address instead of a direct pointer.
The PC address will be converted to a pointer according to the memory
map.
Also pass the block and the current PC to recompiler functions
Drop function lightrec_storeback_all_regs

And make lightrec_storeback_regs store all the registers, as there
won't be a case where we only need to invalidate a part of the register
file.
emitter: Add recompilers for BNE, BEQ, BGTZ, BGEZ, BLTZ, BLEZ
Added a first (and basic) implementation of a block cache
emitter: Fill the __get_jump_address_cb function

It will now return the code address of the next block to execute,
or the exit address if the lightrec_state.stop variable has been set.
Free the block cache on exit