The code in virHashUpdateEntry and virHashAddEntry is really
similar. However, the latter rebalances the hash table when
one of its buckets contains too many elements while the former
does not. Fix this discrepancy.
A couple of allocation were not calling virReportOOMError on allocation
errors
* src/util/hash.c: add the needed call in virHashCreate and
virHashAddOrUpdateEntry
Most of the hash iterators need to modify either payload of
data args. The const annotation prevents this.
* src/util/hash.h, src/util/hash.c: Remove const-ness from
virHashForEach/Iterator
* src/xen/xm_internal.c: Remove bogus casts
