gl_locale_name_canonicalize -Wunterminated-string-initialization

[Grisha Levit]

On macOS with GCC I get:

lib/localename-unsafe.c: In function 'gl_locale_name_canonicalize':
lib/localename-unsafe.c:1345:7: warning: initializer-string for array of 'char' 
truncates NUL terminator but destination lacks 'nonstring' attribute (9 chars 
into 8 available) [-Wunterminated-string-initialization]
 1345 |     { "yue-Hans", "yue" },
      |       ^~~~~~~~~~

This seems like a correct warning based on the struct definition:

  typedef struct { const char langtag[7+1]; const char unixy[12+1]; }
          langtag_entry;

and "yue-Hans" being one char longer than all the other langtags.