rename y16t.h -> y16t_idx.h

idx.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: ISC
-#include "y16t.h"
+#include "y16t_idx.h"
 #include "y16t_internal.h"
 #include <arpa/inet.h>
 #include <errno.h>

meson.build

@@ -4,7 +4,7 @@ project('y16t 16bit-field quad tree library', 'c',
   license : 'Apache-2.0',
   meson_version : '>=0.50')
 
-install_headers('y16t.h')
+install_headers('y16t_idx.h')
 
 c_base_args = [
   '-fno-plt',