Add an easy update script

Author: Perksey

sources/SDL/Native/update.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env -S bash -eu
+if [ ! -e ../../../eng/submodules/sdl/CMakeLists.txt ]; then
+    git submodule update --init --recursive --depth 1 ../../../eng/submodules/sdl
+fi
+verout="$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")/version.txt"
+(
+    cd ../../../eng/submodules/sdl
+    git fetch --tags
+    IFS=' ' read -a latest <<< "$(git for-each-ref --sort=-committerdate --count=1 --contains=HEAD "refs/tags/release-3*")"
+    if [[ "${latest:-}" == "" && "$(git describe --tags --exact-match)" == "preview-"* ]]; then
+        IFS=' ' read -a latest <<< "$(git for-each-ref --sort=-committerdate --count=1 --contains=HEAD "refs/tags/preview-3*")"
+    fi
+    if [[ "${latest:-}" != "" ]]; then
+        git checkout "${latest[0]}"
+        ver="$(git describe --tags --exact-match)"
+        if [[ "$ver" == "preview-"* ]]; then
+          echo "${ver:8}-preview" > "$verout"
+        else
+          echo "${ver:8}" > "$verout"
+        fi
+    fi
+)
+git add ../../../eng/submodules/sdl version.txt

sources/SDL/Native/version.txt

@@ -0,0 +1 @@
+3.1.6-preview