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/sdl3/sdl-libxinput.patch

@@ -0,0 +1,55 @@
+From 8b6b251966b5ea14f9df87c834ffa9ea456b5600 Mon Sep 17 00:00:00 2001
+From: Frank Praznik <frank.praznik@gmail.com>
+Date: Tue, 17 Mar 2026 15:01:56 -0400
+Subject: [PATCH] x11: Fix building when XInput2 is not available
+
+---
+ src/video/x11/SDL_x11xinput2.c | 8 +++++++-
+ 1 file changed, 7 insertions(+), 1 deletion(-)
+
+diff --git a/src/video/x11/SDL_x11xinput2.c b/src/video/x11/SDL_x11xinput2.c
+index c8b37cec98217..5cf75901f2c14 100644
+--- a/src/video/x11/SDL_x11xinput2.c
++++ b/src/video/x11/SDL_x11xinput2.c
+@@ -34,7 +34,6 @@
+ 
+ #ifdef SDL_VIDEO_DRIVER_X11_XINPUT2
+ static bool xinput2_initialized;
+-#endif
+ #if defined(SDL_VIDEO_DRIVER_X11_XINPUT2_SUPPORTS_SCROLLINFO) || defined(SDL_VIDEO_DRIVER_X11_XINPUT2_SUPPORTS_MULTITOUCH)
+ static bool xinput2_scrolling_supported;
+ static bool xinput2_multitouch_supported;
+@@ -137,6 +136,7 @@ static SDL_Window *xinput2_get_sdlwindow(SDL_VideoData *videodata, Window window
+     const SDL_WindowData *windowdata = X11_FindWindow(videodata, window);
+     return windowdata ? windowdata->window : NULL;
+ }
++#endif // SDL_VIDEO_DRIVER_X11_XINPUT2
+ 
+ #ifdef SDL_VIDEO_DRIVER_X11_XINPUT2_SUPPORTS_SCROLLINFO
+ static void xinput2_reset_scrollable_valuators(void)
+@@ -751,12 +751,15 @@ void X11_HandleXinput2Event(SDL_VideoDevice *_this, XGenericEventCookie *cookie)
+ 
+ void X11_InitXinput2Multitouch(SDL_VideoDevice *_this)
+ {
++#ifdef SDL_VIDEO_DRIVER_X11_XINPUT2
+     xinput2_grabbed_touch_raised = false;
+     xinput2_active_touch_count = 0;
++#endif
+ }
+ 
+ bool X11_Xinput2HandlesMotionForWindow(SDL_WindowData *window_data)
+ {
++#ifdef SDL_VIDEO_DRIVER_X11_XINPUT2
+     /* Send the active flag once more after the touch count is zero, to suppress the
+      * emulated motion event when the last touch is raised.
+      */
+@@ -765,6 +768,9 @@ bool X11_Xinput2HandlesMotionForWindow(SDL_WindowData *window_data)
+     xinput2_grabbed_touch_raised = false;
+ 
+     return ret;
++#else
++    return false;
++#endif // SDL_VIDEO_DRIVER_X11_XINPUT2
+ }
+ 
+ void X11_Xinput2Select(SDL_VideoDevice *_this, SDL_Window *window)

extra/sdl3/sdl3.toml

@@ -0,0 +1,59 @@
+[build]
+type = "cmake"
+
+[build.flags]
+build_dir = "build"
+configure = [
+    "-DSDL_STATIC=OFF",
+    "-G Ninja",
+    "-DSDL_RPATH=OFF",
+    "-DSDL_X11_XINPUT=OFF",
+    "-DSDL_X11_XFIXES=OFF",
+    "-DSDL_X11_XTEST=OFF",
+    "-DSDL_X11_XINPUT=OFF",
+]
+no-delete-static = true
+
+[dependencies]
+build = [
+    "cmake",
+    "ninja",
+    "wayland-protocols",
+    "mesa",
+    "alsa-lib",
+    "libxrandr",
+    "libxinerama",
+    "wayland",
+    "libxss",
+    "vulkan-headers",
+]
+optional = [
+    "alsa-lib",
+    "vulkan-driver",
+]
+runtime = [
+    "glibc",
+    "libxext",
+    "libx11",
+    "libgl",
+    "libxrender",
+    "libxcursor",
+    "hidapi",
+    "libusb",
+]
+
+[package]
+description = "A library for portable low-level access to a video framebuffer, audio output, mouse, and keyboard (Version 3)"
+homepage = "https://www.libsdl.org/"
+license = "Zlib"
+name = "sdl3"
+version = "3.4.2"
+
+[[manual_sources]]
+file = "sdl-libxinput.patch"
+
+[[source]]
+extract_dir = "$name-$version"
+sha256 = "ef39a2e3f9a8a78296c40da701967dd1b0d0d6e267e483863ce70f8a03b4050c"
+url = "https://github.com/libsdl-org/SDL/releases/download/release-$version/SDL3-$version.tar.gz"
+patches = [ "sdl-libxinput.patch" ]