Trying to understand what each patch does made me come up with some more
descriptive names:
- Renaming the two disable-xxx patches to a common names makes it immediately
clear that one replaces the other depending on version number.
- findstring was really not descriptive at all.
- hardcode-pgxs-path will be extended with more paths for split outputs in
a later commit. Renaming here already to allow git to better track renames.
Finally replacing HARDCODED_PGXS_PATH with $out/lib in the last patch, makes
it easier to understand what the end result will look like when reading the
patch.