lj_crecord.c: JIT pointer difference for all element sizes
lj_crecord.c: JIT pointer difference for all element sizes

Support JIT for taking the difference between two pointers whose
element sizes are not a power of 2. This was previously an NYI but not
generates code using a division to convert a pointer to an element
number.

The case where the element size is a power of 2 is handled the same
way as before i.e. using a bit-shift instead of a division.

snabbco/snabb,snabbco/snabb,Igalia/snabbswitch,Igalia/snabbswitch,Igalia/snabb,eugeneia/snabb,eugeneia/snabb,snabbco/snabb,alexandergall/snabbswitch,SnabbCo/snabbswitch,snabbco/snabb,Igalia/snabb,Igalia/snabb,SnabbCo/snabbswitch,snabbco/snabb,alexandergall/snabbswitch,Igalia/snabbswitch,eugeneia/snabb,Igalia/snabb,Igalia/snabb,eugeneia/snabb,Igalia/snabb,snabbco/snabb,eugeneia/snabb,Igalia/snabb,SnabbCo/snabbswitch,Igalia/snabbswitch,alexandergall/snabbswitch,alexandergall/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,Igalia/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,Igalia/snabb,SnabbCo/snabbswitch,snabbco/snabb,snabbco/snabb,alexandergall/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch