FLAC now depends on win_utf8_io

Accidently found this missing dependency
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b7dd296..8f83b38 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -119,7 +119,7 @@
     DESTINATION "${CMAKE_INSTALL_DATADIR}/${PROJECT_NAME}/cmake")
 
 file(GLOB FLAC_HEADERS "include/FLAC/*.h")
-file(GLOB FLACXX_HEADERS "include/FLAC++/*.h")
+file(GLOB FLAC++_HEADERS "include/FLAC++/*.h")
 install(FILES ${FLAC_HEADERS} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/FLAC")
-install(FILES ${FLACXX_HEADERS} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/FLAC++")
+install(FILES ${FLAC++_HEADERS} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/FLAC++")
 install(FILES "man/flac.1" "man/metaflac.1" DESTINATION "${CMAKE_INSTALL_MANDIR}")