curl: Use arch-aware CHECK_TYPE_SIZE results

Re-apply the logic change made by commit v2.8.2~536 (Use arch-aware
CHECK_TYPE_SIZE result, 2009-12-17).  The size of some types must be
selected at preprocessing time when building for multiple archs on OS X.
Merge topic 'update-curl' into next

f1c38352 curl: Use arch-aware CHECK_TYPE_SIZE results