Naive approach to fix memview incref/decref asymmetry in transpose

This patch contains test-case along with a blind patch that fixes the test (but
may have other consequences, someone who actually understands the code must
review it).

Original error was:
Fatal Python error: Acquisition count is 0 (line XYZ)

which was caused by refcount error when memview transposition was used on
extension class memoryview attribute.