Skip unused TooManyCooks, it requires newer libcxx

--- cmake/external/CMakeLists.txt.orig	Tue Aug  4 12:34:45 2026
+++ cmake/external/CMakeLists.txt	Tue Aug  4 12:35:00 2026
@@ -49,7 +49,6 @@
 add_checked_subdirectory(rlottie)
 add_checked_subdirectory(rnnoise)
 add_checked_subdirectory(tde2e)
-add_checked_subdirectory(tmc)
 add_checked_subdirectory(ton)
 add_checked_subdirectory(variant)
 add_checked_subdirectory(vpx)
