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/gc/gc.toml

@@ -0,0 +1,30 @@
+[build]
+type = "autotools"
+
+[build.flags]
+configure = [
+    "--enable-cplusplus",
+    "--disable-static",
+]
+post_install = ["""sed 's|GC_MALLOC 1L|gc 3|g' doc/gc.man | install -Dm644 /dev/stdin "$DESTDIR/usr/share/man/man3/gc.3""""]
+
+[dependencies]
+runtime = ["libcxx"]
+
+[package]
+description = "A garbage collector for C and C++"
+homepage = "https://www.hboehm.info/gc/"
+license = [
+    "LicenseRef-GC",
+    "MIT",
+]
+name = "gc"
+version = "8.2.12"
+
+[[source]]
+extract_dir = "$name-$version"
+post_extract = ["cp -rv ../license.txt .", "./autogen.sh"]
+url = "https://github.com/ivmai/bdwgc.git#v$version"
+
+[[manual_sources]]
+url = "https://www.hboehm.info/gc/license.txt"