Update to Fedora 39, update all toolchains

- Base image: Fedora 39
- SCons: 4.5.2
- Linux: GCC 10.2.0 built against glibc 2.19, binutils 2.35.1
- Windows: MinGW 11.0.0, GCC 13.2.1, binutils 2.40
- Web: Emscripten 3.1.39
- Android: Android NDK 23.2.8568313, build-tools 33.0.2, platform android-33, CMake 3.22.1, JDK 17
  CMake 3.22.1, JDK 17
- macOS: Xcode 15.0 with Apple Clang (LLVM 16.0.0), MacOSX SDK 14.0
- iOS: Xcode 15.0 with Apple Clang (LLVM 16.0.0), iPhoneOS SDK 17.0

Switches macOS/iOS builds to use Apple Clang, to maximize compatibility with
upstream Xcode.

Also add gettext which is needed by Godot build scripts to compile PO files
to MO.

build.sh

@@ -7,7 +7,7 @@ source $basedir/setup.sh
 if [ -z "$1" -o -z "$2" ]; then
   echo "Usage: $0 <godot branch> <base distro>"
   echo
-  echo "Example: $0 3.x f35"
+  echo "Example: $0 4.x f39"
   echo
   echo "godot branch:"
   echo "        Informational, tracks the Godot branch these containers are intended for."
@@ -58,9 +58,9 @@ podman_build windows
 podman_build web
 podman_build android
 
-XCODE_SDK=14.1
-OSX_SDK=13.0
-IOS_SDK=16.1
+XCODE_SDK=15
+OSX_SDK=14.0
+IOS_SDK=17.0
 if [ ! -e "${files_root}"/MacOSX${OSX_SDK}.sdk.tar.xz ] || [ ! -e "${files_root}"/iPhoneOS${IOS_SDK}.sdk.tar.xz ] || [ ! -e "${files_root}"/iPhoneSimulator${IOS_SDK}.sdk.tar.xz ]; then
   if [ ! -e "${files_root}"/Xcode_${XCODE_SDK}.xip ]; then
     echo "files/Xcode_${XCODE_SDK}.xip is required. It can be downloaded from https://developer.apple.com/download/more/ with a valid apple ID."