cmake: fix the library search path for bootstrapping libraries

Don't add the architecture to the library search path, because the output path also doesn't contain the architecture (for bootstrapping libraries)

rdar://90025270

Author: eeckstein

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -1214,7 +1214,7 @@ function(add_swift_target_library_single target name)
 
   set(library_search_subdir "${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_LIB_SUBDIR}")
   set(library_search_directories
-      "${lib_dir}/${SWIFTLIB_SINGLE_SUBDIR}"
+      "${lib_dir}/${output_sub_dir}"
       "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/../lib/swift/${SWIFTLIB_SINGLE_SUBDIR}"
       "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/../lib/swift/${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_LIB_SUBDIR}")