Make Threads stub avalible to other platforms

CMake/platforms/ctr/modules/FindThreads.cmake

@@ -1,3 +0,0 @@
-# Stub out the Threads package on the 3DS.
-# 3DS does not have a system threads library but SDL threads are supported.
-add_library(Threads::Threads INTERFACE IMPORTED GLOBAL)

CMake/platforms/n3ds.cmake

@@ -15,6 +15,7 @@ set(NOEXIT ON)
 # 3DS libraries and compile definitions
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/ctr")
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/ctr/modules")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/threads-stub")
 find_package(CITRO3D REQUIRED)
 
 list(APPEND DEVILUTIONX_PLATFORM_SUBDIRECTORIES platform/ctr)

CMake/platforms/threads-stub/FindThreads.cmake

@@ -0,0 +1,3 @@
+# Stub out the Threads package.
+# Some platforms do not have a system threads library but SDL threads are supported.
+add_library(Threads::Threads INTERFACE IMPORTED GLOBAL)