X64Backend: do not emit micro block skip/epilogue code if micro block is unconditional.

[Mireille]

Relevant code:

lunatic/src/backend/x86_64/backend.cpp

Lines 173 to 189 in 2919147

 code->jmp(label_done); 
  
 // If the micro block was skipped advance PC by the number of instructions in it.  
 code->L(label_skip);     
 if (basic_block.key.Thumb()) { 
   code->add( 
     dword[rcx + state.GetOffsetToGPR(Mode::User, GPR::PC)], 
     micro_block.length * sizeof(u16) 
   ); 
 } else { 
   code->add( 
     dword[rcx + state.GetOffsetToGPR(Mode::User, GPR::PC)], 
     micro_block.length * sizeof(u32) 
   ); 
 } 
  
 code->L(label_done);