build: fix typo (IC -> ICU)

Author: compnerd

cmake/modules/AddSwift.cmake

@@ -425,7 +425,7 @@ function(_add_variant_link_flags)
     list(APPEND library_search_directories "${SWIFT_${sdk}_${arch}_ICU_UC_LIBDIR}")
   endif()
   if(NOT "${SWIFT_${LFLAGS_SDK}_${LFLAGS_ARCH}_ICU_I18N}" STREQUAL "")
-    get_filename_component(SWIFT_${sdk}_${arch}_ICU_I18N_LIBDIR "${SWIFT_${sdk}_${arch}_IC_I18N}" DIRECTORY)
+    get_filename_component(SWIFT_${sdk}_${arch}_ICU_I18N_LIBDIR "${SWIFT_${sdk}_${arch}_ICU_I18N}" DIRECTORY)
     list(APPEND library_search_directories "${SWIFT_${sdk}_${arch}_ICU_I18N_LIBDIR}")
   endif()