This is the next stage of OF API clean-up.
OF_getprop_alloc takes element size argument and returns number of elements in
the property. There are valid use cases for such behavior but mostly API
consumers pass 1 as element size to get string properties. What API users would
expect from OF_getprop_alloc is to be a combination of malloc + OF_getprop with
the same semantic of return value. This patch modifies API signature to match
these expectations.
For the valid use cases with element size != 1 and to reduce modification scope
new OF_getprop_calloc function was introduced that behaves the same way
OF_getprop_alloc behaved prior to this patch. The name is tentative
and refers to calloc(3) function. It will be used if better name is
not suggested.