build; correct swift fat library linking on Windows

Windows does not link against the library but the import library.  When
building the target specific bits, we unfortunately do not use the cmake
build infrastructure properly.  This results in us trying to link
against libraries which do not exist.  Redirect the link to the right
files.  This allows us to build swift-reflection-test.

Author: compnerd

cmake/modules/AddSwift.cmake

@@ -2139,11 +2139,19 @@ function(_add_swift_executable_single name)
   # Find the names of dependency library targets.
   #
   # We don't add the ${ARCH} to the target suffix because we want to link
-  # against fat libraries.
-  _list_add_string_suffix(
-      "${SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES}"
-      "-${SWIFT_SDK_${SWIFTEXE_SINGLE_SDK}_LIB_SUBDIR}"
-      SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES_TARGETS)
+  # against fat libraries.  This only works for the Darwin targets as MachO is
+  # the only format with the fat libraries.
+  if(${SWIFTEXE_SINGLE_SDK} IN_LIST SWIFT_APPLE_PLATFORMS)
+    _list_add_string_suffix(
+        "${SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES}"
+        "-${SWIFT_SDK_${SWIFTEXE_SINGLE_SDK}_LIB_SUBDIR}"
+        SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES_TARGETS)
+  else()
+    _list_add_string_suffix(
+        "${SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES}"
+        "-${SWIFT_SDK_${SWIFTEXE_SINGLE_SDK}_LIB_SUBDIR}-${SWIFTEXE_SINGLE_ARCHITECTURE}"
+        SWIFTEXE_SINGLE_LINK_FAT_LIBRARIES_TARGETS)
+  endif()
 
   handle_swift_sources(
       dependency_target