qemu-options: Mark the non-functional -clock option as deprecated

The function is only ignored since QEMU version 1.7.0. Let's mark
it as deprecated, so that we can finally completely remove it soon.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1526990298-17924-1-git-send-email-thuth@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

qemu-doc.texi

@@ -2922,6 +2922,11 @@ The @code{-startdate} option has been replaced by @code{-rtc base=@var{date}}.
 Option @option{-virtioconsole} has been replaced by
 @option{-device virtconsole}.
 
+@subsection -clock (since 3.0.0)
+
+The @code{-clock} option is ignored since QEMU version 1.7.0. There is no
+replacement since it is not needed anymore.
+
 @section qemu-img command line arguments
 
 @subsection convert -s (since 2.0.0)

vl.c

@@ -3713,6 +3713,7 @@ int main(int argc, char **argv, char **envp)
                 /* Clock options no longer exist.  Keep this option for
                  * backward compatibility.
                  */
+                warn_report("This option is ignored and will be removed soon");
                 break;
             case QEMU_OPTION_startdate:
                 warn_report("This option is deprecated, use '-rtc base=' instead.");