patch 8.2.0967: unnecessary type casts for vim_strnsave()

Problem:    Unnecessary type casts for vim_strnsave().
Solution:   Remove the type casts.
diff --git a/src/highlight.c b/src/highlight.c
index 5d123ac..dacce5c 100644
--- a/src/highlight.c
+++ b/src/highlight.c
@@ -963,7 +963,7 @@
 	    break;
 	}
 	vim_free(arg);
-	arg = vim_strnsave(arg_start, (int)(linep - arg_start));
+	arg = vim_strnsave(arg_start, linep - arg_start);
 	if (arg == NULL)
 	{
 	    error = TRUE;
@@ -5003,7 +5003,7 @@
     {
 	p = skiptowhite(eap->arg);
 	if (!eap->skip)
-	    g = vim_strnsave(eap->arg, (int)(p - eap->arg));
+	    g = vim_strnsave(eap->arg, p - eap->arg);
 	p = skipwhite(p);
 	if (*p == NUL)
 	{