typo in comment in gui.c

Problem:  typo in comment in gui.c (after v9.1.1367)
Solution: fix the typo  (Christ van Willegen)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/gui.c b/src/gui.c
index 804d39c..7b61381 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -3835,7 +3835,7 @@
 		    wincount,
 		    modified ? "+" : "");
 
-	    // Make sure resulting NameBuff will not exceed it's bounds.
+	    // Make sure resulting NameBuff will not exceed its bounds.
 	    if (NameBufflen + buflen < MAXPATHL)
 	    {
 		mch_memmove(NameBuff + buflen, NameBuff, NameBufflen + 1);	// +1 for NUL