Fix runtime default variable naming

The names of the variables in `DefaultSettings` should end in `_default`
so that the variable that they are defaulting can be overridden.
Otherwise CMake will just set the value and move on overriding the
setting coming from the commandline/cache file.

Author: etcwilde

Runtimes/Core/cmake/modules/DefaultSettings.cmake

@@ -38,25 +38,25 @@ if(APPLE)
   set(SwiftCore_ENABLE_OBJC_INTEROP_default ON)
   set(SwiftCore_ENABLE_REFLECTION_default ON)
   set(SwiftCore_ENABLE_FATALERROR_BACKTRACE_default ON)
-  set(SwiftCore_ENABLE_RUNTIME_OS_VERSIONING ON)
-  set(SwiftCore_ENABLE_OVERRIDABLE_RETAIN_RELEASE ON)
-  set(SwiftCore_THREADING_PACKAGE "DARWIN")
+  set(SwiftCore_ENABLE_RUNTIME_OS_VERSIONING_default ON)
+  set(SwiftCore_ENABLE_OVERRIDABLE_RETAIN_RELEASE_default ON)
+  set(SwiftCore_THREADING_PACKAGE_default "DARWIN")
   set(SwiftCore_ENABLE_PRESPECIALIZATION_default ON)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "WASM")
   set(SwiftCore_OBJECT_FORMAT_default "elf")
-  set(SwiftCore_THREADING_PACKAGE "NONE")
+  set(SwiftCore_THREADING_PACKAGE_default "NONE")
 elseif(LINUX OR ANDROID OR BSD)
   set(SwiftCore_OBJECT_FORMAT_default "elf")
   set(SwiftCore_ENABLE_FATALERROR_BACKTRACE_default ON)
   if(LINUX)
     set(SwiftCore_THREADING_PACKAGE "LINUX")
     set(SwiftCore_ENABLE_PRESPECIALIZATION_default ON)
   else()
-    set(SwiftCore_THREADING_PACKAGE "PTHREADS")
+    set(SwiftCore_THREADING_PACKAGE_default "PTHREADS")
   endif()
 elseif(WIN32)
   set(SwiftCore_OBJECT_FORMAT_default "coff")
-  set(SwiftCore_THREADING_PACKAGE "WIN32")
+  set(SwiftCore_THREADING_PACKAGE_default "WIN32")
   set(SwiftCore_ENABLE_FATALERROR_BACKTRACE_default ON)
   set(SwiftCore_ENABLE_PRESPECIALIZATION_default ON)
 endif()