doc: Update for FreeBSD 13.0/arm64

[Bruno Haible]

2021-04-18  Bruno Haible  <bruno@clisp.org>

        doc: Update for FreeBSD 13.0/arm64.
        * doc/posix-headers/stdint.texi: Mention FreeBSD 13 bug.
        * m4/stdint.m4: Update comment.

diff --git a/doc/posix-headers/stdint.texi b/doc/posix-headers/stdint.texi
index 6775bea..784799b 100644
--- a/doc/posix-headers/stdint.texi
+++ b/doc/posix-headers/stdint.texi
@@ -15,7 +15,7 @@ This header file is very incomplete on some platforms.
 @item
 The values of @code{SIG_ATOMIC_MIN} and @code{SIG_ATOMIC_MAX} are incorrect
 on some platforms:
-FreeBSD 6.2 / ia64.
+FreeBSD 6.2/ia64, FreeBSD 13.0/arm64.
 @item
 The value of @code{WINT_MAX} is incorrect on some platforms:
 mingw.
diff --git a/m4/stdint.m4 b/m4/stdint.m4
index 3406445..2eb1652 100644
--- a/m4/stdint.m4
+++ b/m4/stdint.m4
@@ -1,4 +1,4 @@
-# stdint.m4 serial 59
+# stdint.m4 serial 60
 dnl Copyright (C) 2001-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -170,7 +170,7 @@ struct s {
       PTRDIFF_MIN == TYPE_MINIMUM (ptrdiff_t)
       && PTRDIFF_MAX == TYPE_MAXIMUM (ptrdiff_t)
       ? 1 : -1;
-  /* Detect bug in FreeBSD 6.0 / ia64.  */
+  /* Detect bug in FreeBSD 6.0/ia64 and FreeBSD 13.0/arm64.  */
   int check_SIG_ATOMIC:
       SIG_ATOMIC_MIN == TYPE_MINIMUM (sig_atomic_t)
       && SIG_ATOMIC_MAX == TYPE_MAXIMUM (sig_atomic_t)