Description

Perform the endian byteswap on the correct buffer area for PSD RLE decoding. The original code used dst but that pointer is modified from its original value as it progresses through decoding.

Fixes #4599

Tests

It might be prudent to add a test for this. Is the repro file attached to the bug too big for this repo(842kb) or do you want them in the oiio-images repo maybe?

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable. (Check if there is no
  need to update the documentation, for example if this is a bug fix that
  doesn't change the API.)
• I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• If I added or modified a C++ API call, I have also amended the
  corresponding Python bindings (and if altering ImageBufAlgo functions, also
  exposed the new functionality as oiiotool options).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format before submitting, I definitely will look at the CI
  test that runs clang-format and fix anything that it highlights as being
  nonconforming.