[PATCH] updwtmp.3: Add #define GNU_SOURCE for updwtmpx

[Sam James <sam@xxxxxxxxxx>]

Closes: https://bugzilla.kernel.org/show_bug.cgi?id=216168
Signed-off-by: Sam James <sam@xxxxxxxxxx>
---
 man3/updwtmp.3 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/man3/updwtmp.3 b/man3/updwtmp.3
index bd84b91cd..175bec772 100644
--- a/man3/updwtmp.3
+++ b/man3/updwtmp.3
@@ -66,6 +66,7 @@ glibc provides (since version 2.1):
 .PP
 .in +4n
 .EX
+.BR "#define _GNU_SOURCE          " "/* See feature_test_macros(7) */"
 .B #include <utmpx.h>
 .BI "void updwtmpx (const char *" wtmpx_file ", const struct utmpx *" utx );
 .EE
-- 
2.36.1