This function doesn't do anything currently so these missing calls are a
latent issue. It could be used for e.g. memory leak checking in the
future though, and it's potentially a useful place to add code when
debugging.
Leave PHP5 wrapping them as integers as this change could cause
incompatibilities.
Fixes issue https://github.com/swig/swig/issues/686 noted by Nishant
Gupta.