[PATCH] close_range.2: Add _GNU_SOURCE and unistd.h to SYNOPSIS

[Mark Wielaard <mark@klomp.org>]

close_range is defined in unistd.h when _GNU_SOURCE is defined.
The linux/close_range.h include file only defines the (linux specific)
flags constants.

Reported-by: Alexandra Hájková <ahajkova@redhat.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 man2/close_range.2 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/man2/close_range.2 b/man2/close_range.2
index 380a47365..fd13ba645 100644
--- a/man2/close_range.2
+++ b/man2/close_range.2
@@ -11,7 +11,10 @@ Standard C library
 .RI ( libc ", " \-lc )
 .SH SYNOPSIS
 .nf
-.B #include <linux/close_range.h>
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BR "#include <linux/close_range.h>" "  /* For the flags constants */"
 .P
 .BI "int close_range(unsigned int " first ", unsigned int " last ,
 .BI "                unsigned int " flags );
-- 
2.43.0