improve verb-tense for explaining the calling convention of __

ok guenther jmc

src/lib/libc/stdlib/realpath.3

@@ -28,9 +28,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: realpath.3,v 1.23 2019/06/30 17:31:39 jmc Exp $
+.\"	$OpenBSD: realpath.3,v 1.24 2019/07/05 12:55:36 deraadt Exp $
 .\"
-.Dd $Mdocdate: June 30 2019 $
+.Dd $Mdocdate: July 5 2019 $
 .Dt REALPATH 3
 .Os
 .Sh NAME
@@ -153,7 +153,7 @@ In
 it was reimplemented on top of the
 .Fn __realpath
 system call.
-Its calling convention differed from the standard
+Its calling convention differs from the standard
 function by requiring
 .Ar resolved
 to not be