RFR: 8214976: Warn about uses of functions replaced for portability

[Kim Barrett]

> On Jan 5, 2022, at 10:32 AM, Harold Seigel <hseigel at openjdk.java.net> wrote:
> Should I remove FORBID_C_FUNCTION(char *strdup(const char*), from this change and revert the strdup changes?  A future bug fix would handle FORBID_C_FUNCTION for strdup(), malloc() and free() together in one change?

That seems like a good idea to me.