Add configuration files and patches for R, SDL2, SDL3, Tk, and Vala

- Introduced `r.toml` for R package configuration, including build flags and dependencies.
- Added `sdl2-compat.toml` for SDL2 compatibility layer with SDL3, specifying build and runtime dependencies.
- Created a patch for SDL3 to handle cases when XInput2 is not available, ensuring compatibility.
- Added `sdl3.toml` for SDL3 configuration, including build flags and dependencies.
- Introduced `tk.toml` for Tk configuration, detailing build flags and runtime dependencies.
- Added a patch for Vala to ensure POSIX compliance in the test runner script, improving portability.

extra/python-sphinx-theme-builder/python-sphinx-theme-builder.toml

@@ -0,0 +1,28 @@
+[build]
+type = "python"
+
+[dependencies]
+build = ["python-flit-core"]
+optional = [
+    "python-click",
+    "python-sphinx-autobuild",
+]
+runtime = [
+    "python",
+    "python-nodeenv",
+    "python-packaging",
+    "python-pyproject-metadata",
+    "python-rich",
+    "python-setuptools",
+]
+
+[package]
+description = "Python build backend for Sphinx themes"
+homepage = "https://github.com/pradyunsg/sphinx-theme-builder"
+license = "MIT"
+name = "python-sphinx-theme-builder"
+version = "0.3.2"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://github.com/pradyunsg/sphinx-theme-builder.git#$version"