patch 8.2.4043: using int for second argument of ga_init2()

Problem:    Using int for second argument of ga_init2().
Solution:   Remove unnessary type cast (int) when using sizeof().
diff --git a/src/help.c b/src/help.c
index fca7cfc..16fbafc 100644
--- a/src/help.c
+++ b/src/help.c
@@ -999,7 +999,7 @@
 
     // If using the "++t" argument or generating tags for "$VIMRUNTIME/doc"
     // add the "help-tags" tag.
-    ga_init2(&ga, (int)sizeof(char_u *), 100);
+    ga_init2(&ga, sizeof(char_u *), 100);
     if (add_help_tags || fullpathcmp((char_u *)"$VIMRUNTIME/doc",
 						dir, FALSE, TRUE) == FPC_SAME)
     {