[test] disable unittests/runtime/Mutex.cpp for single-thread runtime

Author: kateinoigakukun

unittests/runtime/CMakeLists.txt

@@ -84,6 +84,10 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
     endif()
   endif()
 
+  if(NOT SWIFT_STDLIB_SINGLE_THREADED_RUNTIME)
+    list(APPEND PLATFORM_SOURCES Mutex.cpp)
+  endif()
+
   if(SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED)
 #    list(APPEND PLATFORM_SOURCES
 #      DistributedActor.cpp
@@ -98,15 +102,15 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
     weak.mm
     Refcounting.mm
     Actor.cpp
-    TaskStatus.cpp)
+    TaskStatus.cpp
+    Mutex.cpp)
 
   add_swift_unittest(SwiftRuntimeTests
     Array.cpp
     CompatibilityOverrideRuntime.cpp
     CompatibilityOverrideConcurrency.cpp
     Concurrent.cpp
     Metadata.cpp
-    Mutex.cpp
     Enum.cpp
     Refcounting.cpp
     Stdlib.cpp