cmake: we only need a C++ compiler for Android, Haiku and UWP

Our CMake script does (currently) not support NGage, Xbox One, or Xbox Series.

CMakeLists.txt

@@ -8,7 +8,7 @@ endif()
 set(CMAKE_POLICY_DEFAULT_CMP0091 NEW)
 
 # See docs/release_checklist.md
-project(SDL3 LANGUAGES C CXX VERSION "3.0.0")
+project(SDL3 LANGUAGES C VERSION "3.0.0")
 
 if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
   set(SDL3_SUBPROJECT OFF)
@@ -1788,6 +1788,7 @@ elseif(WINDOWS)
   sdl_glob_sources("${SDL3_SOURCE_DIR}/src/core/windows/*.c")
 
   if(WINDOWS_STORE)
+    enable_language(CXX)
     sdl_glob_sources(
       "${SDL3_SOURCE_DIR}/src/core/winrt/*.c"
       "${SDL3_SOURCE_DIR}/src/core/winrt/*.cpp"
@@ -2357,6 +2358,7 @@ elseif(APPLE)
   endif()
 
 elseif(HAIKU)
+  enable_language(CXX)
   if(SDL_AUDIO)
     set(SDL_AUDIO_DRIVER_HAIKU 1)
     sdl_glob_sources("${SDL3_SOURCE_DIR}/src/audio/haiku/*.cc")

build-scripts/test-versioning.sh

@@ -25,7 +25,7 @@ not_ok () {
     failed=1
 }
 
-version=$(sed -Ene 's/^project\(SDL[0-9]+ LANGUAGES C CXX VERSION "([0-9.]*)"\)$/\1/p' CMakeLists.txt)
+version=$(sed -Ene 's/^project\(SDL[0-9]+ LANGUAGES C VERSION "([0-9.]*)"\)$/\1/p' CMakeLists.txt)
 
 if [ "$ref_version" = "$version" ]; then
     ok "CMakeLists.txt $version"

cmake/sdlchecks.cmake

@@ -1068,6 +1068,7 @@ macro(CheckHIDAPI)
 
     if(HAVE_HIDAPI)
       if(ANDROID)
+        enable_language(CXX)
         sdl_sources("${SDL3_SOURCE_DIR}/src/hidapi/android/hid.cpp")
       endif()
       if(IOS OR TVOS)