[Windows] Switch to 'PURE' bridging mode for now

With newer llvm, importing 'llvm/include/llvm/ADT/DynamicAPInt.h' causes
an error:

  C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.39.33519\include\numeric:598:12: error: function '_Select_countr_zero_impl<unsigned long long, (lambda at C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.39.33519\include\numeric:598:55)>' with deduced return type cannot be used before it is defined

Author: rintaro

CMakeLists.txt

@@ -434,7 +434,7 @@ if("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows" AND BOOTSTRAPPING_MODE STREQUAL "HO
 endif()
 
 if(BRIDGING_MODE STREQUAL "DEFAULT" OR NOT BRIDGING_MODE)
-  if(CMAKE_BUILD_TYPE STREQUAL "Debug" OR (CMAKE_Swift_COMPILER AND CMAKE_Swift_COMPILER_VERSION VERSION_LESS 5.8))
+  if(CMAKE_BUILD_TYPE STREQUAL "Debug" OR "${SWIFT_HOST_VARIANT_SDK}" STREQUAL "WINDOWS" OR (CMAKE_Swift_COMPILER AND CMAKE_Swift_COMPILER_VERSION VERSION_LESS 5.8))
     # In debug builds, to workaround a problem with LLDB's `po` command (rdar://115770255).
     # If the host Swift version is less than 5.8, use pure mode to workaround a C++ interop compiler crash.
     set(BRIDGING_MODE "PURE")