Update from gnulib

Update from gnulib

* admin/merge-gnulib (avoided_flags):
* cross/lib/cdefs.h (__bos):
(__glibc_unsigned_or_positive):
(__glibc_unsafe_len):
(__glibc_fortify):
(__glibc_fortify_n):
* cross/lib/isnan.c:
* cross/lib/libc-config.h:
* cross/lib/openat-proc.c (openat_proc_name):
* cross/lib/vasnprintf.c (VASNPRINTF):
* cross/lib/verify.h (_Static_assert):
(_GL_SA3):
* lib/gnulib.mk.in (HAVE_GRANTPT):
(HAVE_SPAWN_H):
(NEXT_AS_FIRST_DIRECTIVE_LIMITS_H):
(NEXT_LIMITS_H):
(REPLACE_GETSUBOPT):
(REPLACE_ILOGB):
(SYSTEM_TYPE):
(BUILT_SOURCES):
* lib/isnan.c:
* lib/vasnprintf.c (VASNPRINTF):
* lib/verify.h (_GL_SA3):
* m4/gnulib-common.m4 (gl_COMMON_BODY):
* m4/gnulib-comp.m4 (gl_INIT): Update from gnulib.