ams: support building unit test programs on windows/linux/macos

libraries/libstratosphere/source/spl/spl_api.cpp

@@ -17,6 +17,9 @@
 
 namespace ams::spl {
 
+    /* BIG TODO: How to deal with this? */
+    #if defined(ATMOSPHERE_OS_HORIZON)
+
     namespace {
 
         enum class InitializeMode {
@@ -295,4 +298,6 @@ namespace ams::spl {
         }
     }
 
+    #endif
+
 }