[build][cmake] Added emscripten build options (#5180)

* [cmake] export automatically raylib definitions and compile/link options

* [cmake] pass emscripten options to consumer project

CMakeLists.txt

@@ -29,7 +29,7 @@ include(CompilerFlags)
 # Registers build options that are exposed to cmake
 include(CMakeOptions.txt)
 
-if (UNIX AND NOT APPLE AND NOT "${PLATFORM}" MATCHES "DRM")
+if (UNIX AND NOT APPLE AND NOT "${PLATFORM}" MATCHES "DRM" AND NOT "${PLATFORM}" MATCHES "Web")
   if (NOT GLFW_BUILD_WAYLAND AND NOT GLFW_BUILD_X11)
     MESSAGE(FATAL_ERROR "Cannot disable both Wayland and X11")
   endif()

src/CMakeLists.txt

@@ -69,7 +69,7 @@ else()
 endif()
 
 if (${PLATFORM} MATCHES "Web")
-    target_link_options(raylib PUBLIC "-sUSE_GLFW=3")
+    target_link_options(raylib PUBLIC "-sUSE_GLFW=3" -sEXPORTED_RUNTIME_METHODS=ccall -sASYNCIFY)
     if(${GRAPHICS} MATCHES "GRAPHICS_API_OPENGL_ES3")
         target_link_options(raylib PUBLIC "-sMIN_WEBGL_VERSION=2")
         target_link_options(raylib PUBLIC "-sMAX_WEBGL_VERSION=2")