add a lib for rendering text in sdl2 and rules to make in makefile

SDL2_ttf/cmake/FindPrivateSDL2.cmake

@@ -0,0 +1,47 @@
+# FIXME: this should be provided by SDL2
+
+include(FindPackageHandleStandardArgs)
+include("${CMAKE_CURRENT_LIST_DIR}/CommonFindSDL2.cmake")
+
+find_library(SDL2_LIBRARY
+    NAMES SDL2
+    HINTS ${SDL2_DIR} ENV SDL2_DIR
+    PATH_SUFFIXES ${_lib_suffixes}
+)
+
+find_path(SDL2_INCLUDE_DIR
+    NAMES SDL_haptic.h
+    PATH_SUFFIXES SDL2
+    HINTS ${SDL2_DIR} ENV SDL2_DIR
+    PATH_SUFFIXES ${_inc_suffixes}
+)
+
+set(SDL2_VERSION)
+if(SDL2_INCLUDE_DIR)
+    file(READ "${SDL2_INCLUDE_DIR}/SDL_version.h" _sdl_version_h)
+    string(REGEX MATCH "#define[ \t]+SDL_MAJOR_VERSION[ \t]+([0-9]+)" _sdl2_major_re "${_sdl_version_h}")
+    set(_sdl2_major "${CMAKE_MATCH_1}")
+    string(REGEX MATCH "#define[ \t]+SDL_MINOR_VERSION[ \t]+([0-9]+)" _sdl2_minor_re "${_sdl_version_h}")
+    set(_sdl2_minor "${CMAKE_MATCH_1}")
+    string(REGEX MATCH "#define[ \t]+SDL_PATCHLEVEL[ \t]+([0-9]+)" _sdl2_patch_re "${_sdl_version_h}")
+    set(_sdl2_patch "${CMAKE_MATCH_1}")
+    if(_sdl2_major_re AND _sdl2_minor_re AND _sdl2_patch_re)
+        set(SDL2_VERSION "${_sdl2_major}.${_sdl2_minor}.${_sdl2_patch}")
+    endif()
+endif()
+
+find_package_handle_standard_args(PrivateSDL2
+    REQUIRED_VARS SDL2_LIBRARY SDL2_INCLUDE_DIR
+    VERSION_VAR SDL2_VERSION
+)
+
+if(PrivateSDL2_FOUND)
+    if(NOT TARGET PrivateSDL2::PrivateSDL2)
+        add_library(PrivateSDL2::PrivateSDL2 UNKNOWN IMPORTED)
+        set_target_properties(PrivateSDL2::PrivateSDL2 PROPERTIES
+            INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIR}"
+            IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+            IMPORTED_LOCATION "${SDL2_LIBRARY}"
+        )
+    endif()
+endif()