cmake: add SDL2 support to cmake build script

cmake/FindSDL2.cmake

@@ -0,0 +1,27 @@
+find_package(PkgConfig QUIET)
+if(PKG_CONFIG_FOUND)
+    pkg_check_modules(SDL2 IMPORTED_TARGET "sdl2")
+    if(TARGET PkgConfig::SDL2 AND NOT TARGET sdl2::sdl2)
+        add_library(_sdl2 INTERFACE)
+        target_link_libraries(_sdl2 INTERFACE PkgConfig::SDL2)
+        add_library(SDL2::SDL2 ALIAS _sdl2)
+    endif()
+endif()
+
+if(NOT SDL2_FOUND)
+    find_path(SDL2_INCLUDE_DIR sdl2.h)
+    find_library(SDL2_LIBRARY sdl2)
+
+    include(FindPackageHandleStandardArgs)
+    find_package_handle_standard_args(libuv
+        REQUIRED_VARS SDL2_INCLUDE_DIR SDL2_LIBRARY
+    )
+
+    if(NOT TARGET SDL2::SDL2)
+        add_library(SDL2::SDL2 UNKNOWN IMPORTED)
+        set_target_properties(SDL2::SDL2 PROPERTIES
+            IMPORTED_LOCATION "${SDL2_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIR}"
+        )
+    endif()
+endif()

cmake/librw-config.cmake.in

@@ -0,0 +1,19 @@
+include("${CMAKE_CURRENT_LIST_DIR}/librw-targets.cmake")
+
+set(LIBRW_PLATFORM "@LIBRW_PLATFORM@")
+set(LIBRW_PLATFORMS "@LIBRW_PLATFORMS@")
+set(LIBRW_PLATFORM_@LIBRW_PLATFORM@ ON)
+
+if(LIBRW_PLATFORM_GL3)
+    set(LIBRW_GL3_GFXLIB "@LIBRW_GL3_GFXLIB@")
+    set(LIBRW_GL3_GFXLIBS "@LIBRW_GL3_GFXLIBS@")
+
+    set(OpenGL_GL_PREFERENCE GLVND)
+    find_package(OpenGL REQUIRED)
+    if(LIBRW_GL3_GFXLIB STREQUAL "GLFW")
+        find_package(GLEW REQUIRED)
+        find_package(glfw3 REQUIRED)
+    elseif(LIBRW_GL3_GFXLIB STREQUAL "GLFW")
+        find_package(SDL2 REQUIRED)
+    endif()
+endif()