This week's `gcc-13` snapshot cleaned further up it's standard headers
and exposed missing declaration as a build failure:
../test/threads/hb-subset-threads.cc: In function 'void test_operation(operation_t, const char*, const test_input_t&)':
../test/threads/hb-subset-threads.cc:127:3: error: 'printf' was not declared in this scope
../test/threads/hb-subset-threads.cc: In function 'int main(int, char**)':
../test/threads/hb-subset-threads.cc:157:19: error: 'atoi' was not declared in this scope