migration/rdma.c's macro ERROR()

[Markus Armbruster <armbru@redhat.com>]

migration/rdma.c has

    /*
     * Print and error on both the Monitor and the Log file.
     */
    #define ERROR(errp, fmt, ...) \
        do { \
            fprintf(stderr, "RDMA ERROR: " fmt "\n", ## __VA_ARGS__); \
            if (errp && (*(errp) == NULL)) { \
                error_setg(errp, "RDMA ERROR: " fmt, ## __VA_ARGS__); \
            } \
        } while (0)

This is problematic.  The point of error_setg() & friends is detectin
errors from handling them.  error.h:

 * - Separation of concerns: the function is responsible for detecting
 *   errors and failing cleanly; handling the error is its caller's
 *   job.  [...]

Reporting the error to stderr violates this principle.  Consequences
include

* When the caller reports the error to stderr, it gets reported there
  twice, possibly in slightly different form.

* When the caller recovers from the error cleanly without reporting it,
  it is reported to stderr anyway, even though it is not actually an
  error.

Mind if I kill the macro?