Allow the 'git-llvm' tool to push to svn from the split repositories

Allow the 'git-llvm' tool to push to svn from the split repositories
for 'test-suite', 'lnt', 'zorg', and 'www'.

This is done by looking at the pathname of the git remote named
'origin', which is not 100% reliable, but should work in most cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@365917 91177308-0d34-0410-b5e6-96231b3b80d8