Rebase notes:
- OpenJPEG support has been re-enabled
- ijs-config custom tool removed (pkg-config is used by default now)
- no API/ABI changes according to upstream
- some patches updated to 'git format-patch' format and renamed
- squashed 'ghostscript-Fontmap.local.patch' into
'ghostscript-9.20-runlibfileifexists.patch'
- rest of patches deleted (irrelevant for current version), mostly
because upstream has fixed those issues in some way
