Install SDL2/SDL3 cmake config only when installing the ports

The cmake config files are logically part of the ports
so install them then the port is installed

This doesn't fix #19780 completely, since trying to build an
SDL2 or SDL3 cmake project will still require some kind of
install step, but it makes it less confusing.

Author: sbc100

tools/ports/__init__.py

@@ -162,6 +162,13 @@ def install_header_dir(src_dir, target=None):
     logger.debug(f'installing headers: {dest}')
     shutil.copytree(src_dir, dest, dirs_exist_ok=True, copy_function=maybe_copy)
 
+  @staticmethod
+  def install_file(filename, target):
+    sysroot = cache.get_sysroot_dir()
+    target_dir = os.path.join(sysroot, os.path.dirname(target))
+    os.makedirs(target_dir, exist_ok=True)
+    maybe_copy(filename, os.path.join(sysroot, target))
+
   @staticmethod
   def install_headers(src_dir, pattern='*.h', target=None):
     logger.debug('install_headers')

tools/ports/sdl2.py

@@ -36,6 +36,9 @@ def create(final):
     source_include_path = os.path.join(src_dir, 'include')
     ports.install_headers(source_include_path, target='SDL2')
 
+    rootdir = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+    ports.install_file(os.path.join(rootdir, 'system/lib/cmake/SDL2/sdl2-config.cmake'), 'lib/cmake/SDL2/sdl2-config.cmake')
+
     # build
     srcs = '''SDL.c SDL_assert.c SDL_dataqueue.c SDL_error.c SDL_guid.c SDL_hints.c SDL_list.c SDL_log.c
     SDL_utils.c atomic/SDL_atomic.c atomic/SDL_spinlock.c audio/SDL_audio.c audio/SDL_audiocvt.c

tools/ports/sdl3.py

@@ -44,6 +44,9 @@ def create(final):
     source_include_path = os.path.join(root_dir, 'include', 'SDL3')
     ports.install_headers(source_include_path, target='SDL3')
 
+    rootdir = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+    ports.install_file(os.path.join(rootdir, 'system/lib/cmake/SDL3/sdl3-config.cmake'), 'lib/cmake/SDL3/sdl3-config.cmake')
+
     glob_patterns = [
       # Generic sources (from SDL3's CMakeLists.txt)
       '*.c',

tools/system_libs.py

@@ -2493,10 +2493,6 @@ def install_system_headers(stamp):
   bin_dest = cache.get_sysroot_dir('bin')
   copytree_exist_ok(bin_src, bin_dest)
 
-  cmake_src = utils.path_from_root('system/lib/cmake')
-  cmake_dest = cache.get_sysroot_dir('lib/cmake')
-  copytree_exist_ok(cmake_src, cmake_dest)
-
   # Create a version header based on the emscripten-version.txt
   version_file = cache.get_include_dir('emscripten/version.h')
   utils.write_file(version_file, textwrap.dedent(f'''\