cmake: bump minimum required CMake version to 3.16

main features:

- No more sdl-build-options/sdl-shared-build-options/sdl-global-options
- Dependency information is stored on SDL3-collector for sdl3.pc
- Use helper functions to modify the SDL targets;
    - sdl_sources to add sources
    - sdl_glob_sources to add glob soruces
    - sdl_link_dependency to add a link dependency that might also
      appear in sdl3.pc/SDL3Config.cmake
    - sdl_compile_definitions to add macro's
    - sdl_compile_options for compile options
    - sdl_include_directories for include directories
  They avoid repeated checks for existence of the SDL targets
- A nice feature of the previous is the ability to generate
  a sdl3.pc or SDL3Config.cmake that describes its dependencies
  accurately.

various:

- remove duplicate libc symbol list
- add CheckVulkan
- remove unused HAVE_MPROTECT
- add checks for getpagesize

cmake/SDL3Config.cmake.in

@@ -23,19 +23,28 @@ if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL3sharedTargets.cmake")
   set(SDL3_SDL3-shared_FOUND TRUE)
 endif()
 
+macro(find_sdl3_static_dependencies)
+@SDL_FIND_PKG_CONFIG_COMMANDS@
+endmacro()
+
 # Find SDL3::SDL3-static
 if(_sdl3_framework)
+  set(SDL3_SDL3-static_FOUND TRUE)
+  find_sdl3_static_dependencies()
   find_package(SDL3-static CONFIG)
-  if(SDL3-static_FOUND)
+  if(SDL3_SDL3-static_FOUND AND SDL3-static_FOUND)
     set(SDL3_SDL3-static_FOUND TRUE)
   endif()
 else()
   if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL3staticTargets.cmake")
-    if(ANDROID OR HAIKU)
-      enable_language(CXX)
-    endif()
-    include("${CMAKE_CURRENT_LIST_DIR}/SDL3staticTargets.cmake")
     set(SDL3_SDL3-static_FOUND TRUE)
+    find_sdl3_static_dependencies()
+    if(SDL3_SDL3-static_FOUND)
+      if(ANDROID OR HAIKU)
+        enable_language(CXX)
+      endif()
+      include("${CMAKE_CURRENT_LIST_DIR}/SDL3staticTargets.cmake")
+    endif()
   endif()
 endif()
 
@@ -52,21 +61,14 @@ if(_sdl3_framework)
   endif()
 else()
   if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL3testTargets.cmake")
-    include("${CMAKE_CURRENT_LIST_DIR}/SDL3testTargets.cmake")
     set(SDL3_SDL3_test_FOUND TRUE)
+@SDL_TEST_FIND_PKG_CONFIG_COMMANDS@
+    if(SDL3_SDL3_test_FOUND)
+      include("${CMAKE_CURRENT_LIST_DIR}/SDL3testTargets.cmake")
+    endif()
   endif()
 endif()
 
-include("${CMAKE_CURRENT_LIST_DIR}/sdlfind.cmake")
-
-set(SDL_ALSA @SDL_ALSA@)
-set(SDL_ALSA_SHARED @SDL_ALSA_SHARED@)
-if(SDL_ALSA AND NOT SDL_ALSA_SHARED AND TARGET SDL3::SDL3-static)
-  sdlFindALSA()
-endif()
-unset(SDL_ALSA)
-unset(SDL_ALSA_SHARED)
-
 check_required_components(SDL3)
 
 function(_sdl_create_target_alias_compat NEW_TARGET TARGET)