Disable subset tests on cmake for now.

test/subset/CMakeLists.txt

@@ -2,8 +2,9 @@ if (HB_BUILD_UTILS)
   file (READ "${CMAKE_CURRENT_SOURCE_DIR}/data/Makefile.sources" SOURCES)
   extract_make_variable (TESTS ${SOURCES})
   foreach (test IN ITEMS ${TESTS})
-    add_test (NAME ${test}
-      COMMAND python run-tests.py $<TARGET_FILE:hb-subset> "data/${test}"
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+# TODO(grieger): Re-enable once ttx is available in CI environments.
+#    add_test (NAME ${test}
+#      COMMAND python run-tests.py $<TARGET_FILE:hb-subset> "data/${test}"
+#      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
   endforeach ()
 endif ()