SDL: cmake: detect Emscripten architecture as emscripten

SDL Commits
1 
From 25b723cc8252f22f361c630d8cec827b9dab9b2f Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Mon, 30 Jan 2023 19:13:40 +0100
Subject: [PATCH] cmake: detect Emscripten architecture as emscripten

---
 cmake/CheckCPUArchitecture.cmake | 2 ++
 cmake/sdlplatform.cmake          | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/cmake/CheckCPUArchitecture.cmake b/cmake/CheckCPUArchitecture.cmake
index 1eebbd4f07dc..013287424365 100644
--- a/cmake/CheckCPUArchitecture.cmake
+++ b/cmake/CheckCPUArchitecture.cmake
@@ -34,6 +34,8 @@ function(check_cpu_architecture ARCH VARIABLE)
     _internal_check_cpu_architecture("defined(__aarch64__) || defined(_M_ARM64)" arm64 ${VARIABLE})
   elseif(ARCH STREQUAL "loongarch64")
     _internal_check_cpu_architecture("defined(__loongarch64)" loongarch64 ${VARIABLE})
+  elseif(ARCH STREQUAL "emscripten")
+    _internal_check_cpu_architecture("defined(__EMSCRIPTEN__)" emscripten ${VARIABLE})
   else()
     message(WARNING "Unknown CPU architectures (${ARCH}).")
     set(${VARIABLE} FALSE)
diff --git a/cmake/sdlplatform.cmake b/cmake/sdlplatform.cmake
index 551915cc83d6..46720edff7e3 100644
--- a/cmake/sdlplatform.cmake
+++ b/cmake/sdlplatform.cmake
@@ -52,6 +52,8 @@ macro(SDL_DetectCMakePlatform)
     set(SDL_CMAKE_PLATFORM Minix)
   elseif(CMAKE_SYSTEM_NAME MATCHES "Android.*")
     set(SDL_CMAKE_PLATFORM Android)
+  elseif(CMAKE_SYSTEM_NAME MATCHES "Emscripten.*")
+    set(SDL_CMAKE_PLATFORM Emscripten)
   elseif(CMAKE_SYSTEM_NAME MATCHES "BeOS.*")
     message_error("BeOS support has been removed as of SDL 2.0.2.")
   endif()
@@ -76,7 +78,7 @@ function(SDL_DetectCPUArchitecture)
     endforeach()
   endif()
 
-  set(sdl_known_archs x86 x64 arm32 arm64 loongarch64)
+  set(sdl_known_archs x86 x64 arm32 arm64 loongarch64 emscripten)
   if(NOT sdl_cpu_names)
     set(found FALSE)
     foreach(sdl_known_arch ${sdl_known_archs})