patch 8.2.4084: memory leak when looking for autoload prefixed variable

Problem:    Memory leak when looking for autoload prefixed variable.
Solution:   Free the concatenated string.
diff --git a/src/evalvars.c b/src/evalvars.c
index 92dcd76..d111b80 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2889,6 +2889,7 @@
 	    {
 		ht = &globvarht;
 		ret = find_var_in_ht(ht, *name, auto_name, TRUE);
+		vim_free(auto_name);
 		if (ret != NULL)
 		{
 		    if (htp != NULL)
@@ -2896,7 +2897,6 @@
 		    return ret;
 		}
 	    }
-	    vim_free(auto_name);
 	}
     }