Our use of SQLite explicitly avoids using MSVC's _msize which the lib would
notrmally use. This was set up this way in BZ bug 719579 for legitimate reasons
(because _msize would end up using the system symbol, which would crash trying
to get the size information from jemalloc allocations). Since we build the
SQLite lib separately there is no easy way to avoid this warning as it's not
directly linked against mozglue.dll which has the jemalloc functions it wants
for _msize when not using the system allocator. It is implicitly assuming the
function is an extern returning an int (with the call specifically casting to
int) which is correct (well, correct _enough_, anyway) so the warning can
safely be ignored for our specific use as it all lines up at link time.
