have_struct_member: checking for struct stat.st_birthtimespec in sys/stat.h... -------------------- no

"gcc -I../../.ext/include/x86_64-linux -I../.././include -I../.././ext/pathname     -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat  -fPIC   -c conftest.c"
conftest.c:6:35: error: ‘struct stat’ has no member named ‘st_birthtimespec’
 int s = (char *)&((struct stat*)0)->st_birthtimespec - (char *)0;
                                   ^~
checked program was:
/* begin */
 1: #include "ruby.h"
 2: 
 3: #include <sys/stat.h>
 4: 
 5: /*top*/
 6: int s = (char *)&((struct stat*)0)->st_birthtimespec - (char *)0;
 7: int main(int argc, char **argv)
 8: {
 9:   return 0;
10: }
/* end */

--------------------

extconf.h is:
/* begin */
1: #ifndef EXTCONF_H
2: #define EXTCONF_H
3: #endif
/* end */