InputCommon: Update to use SDL3 and bump the SDL submodule in Externals to release-3.2.16.

Flatpak/SDL2/SDL2.json

@@ -1,21 +0,0 @@
-{
-  "name": "SDL2",
-  "buildsystem": "autotools",
-  "config-opts": ["--disable-static"],
-  "sources": [
-    {
-      "type": "dir",
-      "path": "../../Externals/SDL/SDL"
-    }
-  ],
-  "cleanup": [ "/bin/sdl2-config",
-               "/include",
-               "/lib/libSDL2.la",
-               "/lib/libSDL2main.a",
-               "/lib/libSDL2main.la",
-               "/lib/libSDL2_test.a",
-               "/lib/libSDL2_test.la",
-               "/lib/cmake",
-               "/share/aclocal",
-               "/lib/pkgconfig"]
-}

Flatpak/org.DolphinEmu.dolphin-emu.yml

@@ -37,10 +37,6 @@ modules:
           project-id: 20540
           stable-only: true
           url-template: https://www.freedesktop.org/software/libevdev/libevdev-$version.tar.xz
-
-  # build the vendored SDL2 from Externals until the runtime gets 2.30.9
-  - SDL2/SDL2.json
-
   - name: dolphin-emu
     buildsystem: cmake-ninja
     builddir: true