patch 8.2.2907: memory leak when running out of memory

Problem:    Memory leak when running out of memory.
Solution:   Free the allocated memory. (Dominique Pellé, closes #8284)
diff --git a/src/term.c b/src/term.c
index 0a4e5b7..a91d2c7 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4248,6 +4248,7 @@
 	if (new_tc == NULL)
 	{
 	    tc_max_len -= 20;
+	    vim_free(s);
 	    return;
 	}
 	for (i = 0; i < tc_len; ++i)