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/libxcursor/libxcursor.toml

@@ -0,0 +1,21 @@
+[build]
+type = "autotools"
+
+[dependencies]
+runtime = [ "libxfixes", "libxrender", "default-cursors", "libx11", "glibc", "xorgproto" ]
+build = [ "xorg-util-macros" ]
+
+[build.flags]
+configure = ["--disable-static"]
+
+[package]
+description = "X cursor management library"
+homepage = "https://gitlab.freedesktop.org/xorg/lib/libxcursor"
+license = "HPND-sell-variant"
+name = "libxcursor"
+version = "1.2.3"
+
+[[source]]
+extract_dir = "$name-$version"
+sha256 = "fde9402dd4cfe79da71e2d96bb980afc5e6ff4f8a7d74c159e1966afb2b2c2c0"
+url = "https://xorg.freedesktop.org//releases/individual/lib/libXcursor-$version.tar.xz"