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/giflib/build.sh

@@ -0,0 +1,7 @@
+sed -e 's|giflib.xml|giflib.7|' \
+      -re 's|doc/(.*).xml|doc/\1.1|g' \
+      -i Makefile
+make
+make PREFIX=/usr DESTDIR="$DESTDIR" install
+
+

extra/giflib/giflib.toml

@@ -0,0 +1,26 @@
+[build]
+type = "custom"
+
+[build.flags]
+replace_cflags = [ "_FORTIFY_SOURCE=3=_FORTIFY_SOURCE=2" ]
+no-compress-man = true
+
+[dependencies]
+build = [
+    "xmlto",
+    "docbook-xml",
+    "docbook-xsl",
+]
+runtime = ["glibc"]
+
+[package]
+description = "Library for reading and writing gif images"
+homepage = "http://giflib.sourceforge.net"
+license = "MIT"
+name = "giflib"
+version = "6.1.2"
+
+[[source]]
+extract_dir = "$name-$version"
+sha256 = "2421abb54f5906b14965d28a278fb49e1ec9fe5ebbc56244dd012383a973d5c0"
+url = "https://sourceforge.net/projects/giflib/files/giflib-6.x/giflib-$version.tar.gz"