simple cmake change

[bjadamson]

Hi, in my project I use freetype, so to make that work I had un-hardcode the vendored logic.

SDL_ttf/CMakeLists.txt

Lines 351 to 354 in a42434b

	if(NOT EXISTS "${PROJECT_SOURCE_DIR}/external/freetype/CMakeLists.txt")
	message(FATAL_ERROR "No freetype sources found. Install a freetype development package or run the download script in the external folder.")
	endif()
	add_subdirectory(external/freetype external/freetype-build EXCLUDE_FROM_ALL)

To this:

if(NOT EXISTS "${PROJECT_SOURCE_DIR}/../freetype/CMakeLists.txt")
            message(FATAL_ERROR "No freetype sources found. Install a freetype development package or run the download script in the external folder.")
        endif()
        add_subdirectory(../freetype freetype-build EXCLUDE_FROM_ALL)

Hardcoding the directory for freetype doesn't work for me. Hopefully you can do something with this. Good day!

[madebr]

Can you try #640?
It will use targets from your own vendored directory, and not ourse when you configure with SDLTTF_VENDORED=OFF (From SDL_ttf's standpoint, we're not vendoring anything)