Fix illegal early call to PyBuffer_Release in swig typemaps

Summary:
The buffer protocol does not allow us to just call PyBuffer_Release
and assume the buffer will still be there.   Most things that implement the
buffer protocol will let us get away with that, but not all.   We need
to release it at the end of the SWIG wrapper.

Reviewers: labath, jasonmolenda, JDevlieghere, vadimcn

Reviewed By: labath

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D77480