Fix build break on MacOSX
Fix build break on MacOSX

sigar_inet_ntop needs arpa/inet.h

Change-Id: I1db3b44d2281bde79d7d3c014911a5426773d61d
Reviewed-on: https://review.couchbase.org/c/sigar/+/166232
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@couchbase.com>

couchbase/sigar,couchbase/sigar