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/if_perl.xs b/src/if_perl.xs
index ef02730..9a99fc0 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -1435,7 +1435,7 @@
     char_u *str;
     PerlIOVim * s = PerlIOSelf(f, PerlIOVim);
 
-    str = vim_strnsave((char_u *)vbuf, (int)count);
+    str = vim_strnsave((char_u *)vbuf, count);
     if (str == NULL)
 	return 0;
     msg_split((char_u *)str, s->attr);