stdlib: enable cxxshim for Windows

This is used by the test suite and needs to be enabled for Windows to
enable parts of the test suite.

Author: compnerd

stdlib/public/Cxx/cxxshim/CMakeLists.txt

@@ -1,10 +1,5 @@
-is_sdk_requested(WINDOWS swift_build_windows)
 set(libcxxshim_modulemap_target_list)
 foreach(sdk ${SWIFT_SDKS})
-  if(swift_build_windows)
-    continue()
-  endif()
-
   foreach(arch ${SWIFT_SDK_${sdk}_ARCHITECTURES})
     set(arch_suffix "${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${arch}")
     set(arch_subdir "${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}")