* Avoid checking twice if divisor is zero
The flambda branch before merging assumed that Pdivint and Pmodint where
already checked when entering Cmmgen. This was not the case anymore
after merging and this change was lost. This fix this overlook by adding
an annotation to the Pdivint and Pmodint primitive telling whether the
division by zero was already checked.
The reason to move the test generation to Closure_conversion in the
flambda branch was to allow the division primitive to be considered as
pure without needing to check for the effective value of the
divisor. This simplified Semantics_of_primitives a lot.
* Bigarray div and mod also carry safety information
* Handle bigint div and mod like int div and mod in closure_conversion
* Update Changes
* Test for divisions by zero
* Turn Pdivbint and Pmodbint argument into an inline record