trace: don't pretend success if it's not enabled

Partially reverts d33d7616 Don't fail when tracing is disabled

Commit d33d7616

 fixed the problem that the initialization of
libcrypto failed when tracing was disabled, because the unoperational
ossl_trace_init() function returned a failure code. The problem was
fixed by changing its return value from failure to success.

As part of the fix the return values of other unimplemented trace API
functions (like OSSL_trace_set_channel(),OSSL_trace_set_callback())
was changed from failure to success, too. This change was not necessary
and is a bit problematic IMHO, because nobody expects an unimplemented
function to pretend it succeeded.

It's the application's duty to handle the case correctly when the trace
API is not enabled (i.e., OPENSSL_NO_TRACE is defined), not the API's job
to pretend success just to prevent the application from failing.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8552)