Remove redundant value replacing from the VM

There's no point of replacing a register with itself.

*regs[x] = *regs[x]

Author: adazem009

src/engine/virtualmachine_p.cpp

@@ -330,31 +330,26 @@ do_loop_end : {
     DISPATCH();
 
 do_add:
-    REPLACE_RET_VALUE(*READ_REG(0, 2), 2);
     READ_REG(0, 2)->add(*READ_REG(1, 2));
     FREE_REGS(1);
     DISPATCH();
 
 do_subtract:
-    REPLACE_RET_VALUE(*READ_REG(0, 2), 2);
     READ_REG(0, 2)->subtract(*READ_REG(1, 2));
     FREE_REGS(1);
     DISPATCH();
 
 do_multiply:
-    REPLACE_RET_VALUE(*READ_REG(0, 2), 2);
     READ_REG(0, 2)->multiply(*READ_REG(1, 2));
     FREE_REGS(1);
     DISPATCH();
 
 do_divide:
-    REPLACE_RET_VALUE(*READ_REG(0, 2), 2);
     READ_REG(0, 2)->divide(*READ_REG(1, 2));
     FREE_REGS(1);
     DISPATCH();
 
 do_mod:
-    REPLACE_RET_VALUE(*READ_REG(0, 2), 2);
     READ_REG(0, 2)->mod(*READ_REG(1, 2));
     FREE_REGS(1);
     DISPATCH();