error: Restore error_printf()'s function comment

Lost in commit 397d30e940 (qemu-error: remove dependency of stubs on
monitor) many moons ago.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20260114124713.3308719-3-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[Trivial conflict with commit a582a5784e (monitor: move
error_vprintf back to error-report.c) resolved]

util/error-report.c

@@ -70,6 +70,9 @@ int error_vprintf(const char *fmt, va_list ap)
     return error_vprintf_mon(monitor_cur(), fmt, ap);
 }
 
+/*
+ * Print to the current HMP monitor if we have one, else to stderr.
+ */
 int error_printf(const char *fmt, ...)
 {
     va_list ap;