Silence -Wswitch warnings

TypeSystemClang.cpp:4074:11: error: enumeration value 'CountAttributed' not handled in switch [-Werror,-Wswitch]
 4074 |   switch (qual_type->getTypeClass()) {
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~
TypeSystemClang.cpp:4755:11: error: enumeration value 'CountAttributed' not handled in switch [-Werror,-Wswitch]
 4755 |   switch (qual_type->getTypeClass()) {
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~
TypeSystemClang.cpp:5088:11: error: enumeration value 'CountAttributed' not handled in switch [-Werror,-Wswitch]
 5088 |   switch (qual_type->getTypeClass()) {
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~