tdf#121780: com.sun.star.comp.sfx2.BackingComp needs to be registered always

...instead of never (as there is no handling of
org/openoffice/Office/ProtocolHandler-start.xcu in
officecfg/Configuration_officecfg.mk).  That install:module="start" included in
d930cefbe65d8b7f21100fcbf2ddcd977dd15cb1 "Startcenter: Refresh RecentDocsView
when select 'Clear list' menu option" was probably misguided cargo-cult-copying
from (meaningful) install:module="impress" that were already present in
officecfg/registry/data/org/openoffice/Office/ProtocolHandler.xcu.

Change-Id: I03ed0cf84b576597a7b88ee6627a12cedbca4960
Reviewed-on: https://gerrit.libreoffice.org/67224
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit dbc92eab4d1e11fcb1588d80cb118951a180e808)
Reviewed-on: https://gerrit.libreoffice.org/67238
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
diff --git a/officecfg/registry/data/org/openoffice/Office/ProtocolHandler.xcu b/officecfg/registry/data/org/openoffice/Office/ProtocolHandler.xcu
index 62f7566..3e64280 100644
--- a/officecfg/registry/data/org/openoffice/Office/ProtocolHandler.xcu
+++ b/officecfg/registry/data/org/openoffice/Office/ProtocolHandler.xcu
@@ -70,7 +70,7 @@
        <value>vnd.com.sun.star.comp.PresentationMinimizer:*</value>
      </prop>
    </node>
    <node oor:name="com.sun.star.comp.sfx2.BackingComp" oor:op="replace" install:module="start">
    <node oor:name="com.sun.star.comp.sfx2.BackingComp" oor:op="replace">
      <prop oor:name="Protocols">
        <value>vnd.org.libreoffice.recentdocs:*</value>
      </prop>