qemu-option: introduce qemu_opt_set_err()

This is like qemu_opt_set(), except that it takes an Error argument.

This new function allows for a incremental conversion of code using
qemu_opt_set().

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-By: Laszlo Ersek <lersek@redhat.com>
diff --git a/qemu-option.c b/qemu-option.c
index 7af2b50..1cddb9d 100644
--- a/qemu-option.c
+++ b/qemu-option.c
@@ -669,6 +669,12 @@
     return 0;
 }
 
+void qemu_opt_set_err(QemuOpts *opts, const char *name, const char *value,
+                      Error **errp)
+{
+    opt_set(opts, name, value, false, errp);
+}
+
 int qemu_opt_set_bool(QemuOpts *opts, const char *name, bool val)
 {
     QemuOpt *opt;