Ignore *any* errors that occur while trying to self.terminate() a
ScopedPopen instance. This fixes Py2 vs Py3 compatibility, in a way.

git-svn-id: https://svn.nmap.org/nmap-exp/d33tah/ncat-test-py@32617 e0a8ed71-7df4-0310-8962-fdc924857419