Problem with raw APR nonblocking I/O test in INTEGRATION_TEST_llprocess

[Max Fox]

Not sure what the proper fix would be, but there is a logic error in
this test that shows up in mixed python environments.

All the other scripts and tests in the viewer code properly use the
python found by cmake, but this one test is simply trying to run
'python' directly from the path, and finding the wrong one. (python.exe
on the path is 310 here)

I fixed it in my test build by changing line 384 to
argv.push_back("python27"); but it seems like the test should ideally
be fixed by someone that understands the test code better to just use
whatever exe cmake found rather than assume the path will have a
compatibly old python.exe on it.

Max