Utility to manipulate netns on linux kernels that support it


git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@11152 ddefafc4-47db-0310-ae44-fa13212b10f2
added netns scope/context to Uri and Tuple


git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@11153 ddefafc4-47db-0310-ae44-fa13212b10f2
Set and preserve netns context as needed in stack.
Currently only tested for TCP.


git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@11154 ddefafc4-47db-0310-ae44-fa13212b10f2
ignore testSipStackNetNs


git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@11155 ddefafc4-47db-0310-ae44-fa13212b10f2