tkill.2: glibc 2.30 provides a wrapper for tgkill()

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/tkill.2

@@ -37,7 +37,9 @@ tkill, tgkill \- send a signal to a thread
 .fi
 .PP
 .IR Note :
-There are no glibc wrappers for these system calls; see NOTES.
+There is no glibc wrapper for
+.BR tkill ();
+see NOTES.
 .SH DESCRIPTION
 .BR tgkill ()
 sends the signal
@@ -120,6 +122,10 @@ is a real-time signal.
 is supported since Linux 2.4.19 / 2.5.4.
 .BR tgkill ()
 was added in Linux 2.5.75.
+.PP
+Library support for
+.BR tgkill ()
+was added to glibc in version 2.30.
 .SH CONFORMING TO
 .BR tkill ()
 and
@@ -133,8 +139,12 @@ in
 .BR clone (2)
 for an explanation of thread groups.
 .PP
-Glibc does not provide wrappers for these system calls; call them using
+Glibc does not provide a wrapper for
+.BR tkill ();
+call it using
 .BR syscall (2).
+Before glibc 2.30, there was also no wrapper function for
+.BR tgkill ().
 .SH SEE ALSO
 .BR clone (2),
 .BR gettid (2),