message: include locale.h in IOHandler.cpp
  This is needed for the setlocale() call, and it seems that it is not
  transitively pulled in for some build configurations.
diff: #include <assert.h> // for assert
  #include <ctype.h> // for isspace
  #include <errno.h> // for EINTR, errno
  +#include <locale.h> // for setlocale
  #include <stdint.h> // for uint32_t, UINT32_MAX
  #include <stdio.h> // for size_t, fprintf, feof
  #include <string.h> // for strlen
  