Adds an optional second parameter to `node::Malloc()` and
an optional third parameter to `node::Realloc()` giving the
size/number of items to be allocated, in the style of `calloc(3)`.

Use a proper overflow check using division;
the previous `CHECK_GE(n * size, n);` would not detect all cases
of overflow (e.g. `size == SIZE_MAX / 2 && n == 3`).

Backport-PR-URL: #16587
PR-URL: #8482
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

Pass the desired return type directly to the allocation functions,
so that the resulting `static_cast` from `void*` becomes unneccessary
and the return type can be use as a reasonable default value for the
`size` parameter.

Backport-PR-URL: #16587
PR-URL: #8482
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

Provide shortcut `node::CheckedMalloc()` and friends that
replace `node::Malloc()` + `CHECK_NE(·, nullptr);` combinations
in a few places.

Backport-PR-URL: #16587
PR-URL: #8482
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

Call `v8::Isolate::GetCurrent()->LowMemoryNotification()` when
an allocation fails to give V8 a chance to clean up and return
memory before retrying (and possibly giving up).

Backport-PR-URL: #16587
PR-URL: #8482
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>