games/libretro-shaders-glsl: Update to g20260330 and adopt port

• Adopt port
• Update COMMENT and pkg-descr to point out that the shaders originate from the libretro project, but that they can also be used by other projects, e.g. ScummVM.
• Use short hash for GH_TAGNAME. This follows the Porter's Handbook more closely.
• Set DATADIR to its actual non-standard directory.
• The shaders are architecture-independend and there's nothing to build, so set NO_ARCH and NO_BUILD.
• Use COPYTREE_SHARE for installing to ensure proper file ownership and permissions, and to not require the make binary. In this case do not extract unneeded build and CI files by excluding them via EXTRACT_AFTER_ARGS.
• Remove obsolete Makefile patch.

Changelog:
https://github.com/libretro/glsl-shaders/compare/e66776c...bf52cc8

PR: 294140