Add searchbox option to replace_macros.py.
Add searchbox option to replace_macros.py.

Search boxes in documentation are useful when search feature is
available, but it's useless when we host the documentation statically.
Add this option so we can generate search-free version of the
documentation.

Change-Id: I35aadee989ae04b7bbcffd67011634cd0dd085c1

dwhipstock/gerrit,Seinlin/gerrit,gcoders/gerrit,jackminicloud/test,qtproject/qtqa-gerrit,thesamet/gerrit,pkdevbox/gerrit,netroby/gerrit,renchaorevee/gerrit,Seinlin/gerrit,supriyantomaftuh/gerrit,Overruler/gerrit,Overruler/gerrit,MerritCR/merrit,dwhipstock/gerrit,TonyChai24/test,netroby/gerrit,renchaorevee/gerrit,jackminicloud/test,dwhipstock/gerrit,supriyantomaftuh/gerrit,Overruler/gerrit,anminhsu/gerrit,dwhipstock/gerrit,Seinlin/gerrit,TonyChai24/test,GerritCodeReview/gerrit,supriyantomaftuh/gerrit,joshuawilson/merrit,thesamet/gerrit,pkdevbox/gerrit,thesamet/gerrit,hdost/gerrit,TonyChai24/test,joshuawilson/merrit,WANdisco/gerrit,Distrotech/gerrit,qtproject/qtqa-gerrit,thesamet/gerrit,netroby/gerrit,pkdevbox/gerrit,pkdevbox/gerrit,GerritCodeReview/gerrit,renchaorevee/gerrit,gcoders/gerrit,gerrit-review/gerrit,joshuawilson/merrit,renchaorevee/gerrit,hdost/gerrit,gerrit-review/gerrit,joshuawilson/merrit,jackminicloud/test,anminhsu/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,MerritCR/merrit,pkdevbox/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,TonyChai24/test,GerritCodeReview/gerrit,joshuawilson/merrit,MerritCR/merrit,jackminicloud/test,renchaorevee/gerrit,thesamet/gerrit,thinkernel/gerrit,quyixia/gerrit,joshuawilson/merrit,Seinlin/gerrit,supriyantomaftuh/gerrit,Distrotech/gerrit,supriyantomaftuh/gerrit,pkdevbox/gerrit,renchaorevee/gerrit,MerritCR/merrit,hdost/gerrit,Distrotech/gerrit,Distrotech/gerrit,TonyChai24/test,GerritCodeReview/gerrit,quyixia/gerrit,TonyChai24/test,Overruler/gerrit,quyixia/gerrit,gcoders/gerrit,WANdisco/gerrit,Overruler/gerrit,GerritCodeReview/gerrit,gerrit-review/gerrit,thinkernel/gerrit,gcoders/gerrit,hdost/gerrit,quyixia/gerrit,Seinlin/gerrit,netroby/gerrit,gcoders/gerrit,thesamet/gerrit,TonyChai24/test,WANdisco/gerrit,Distrotech/gerrit,qtproject/qtqa-gerrit,thinkernel/gerrit,quyixia/gerrit,jackminicloud/test,supriyantomaftuh/gerrit,thinkernel/gerrit,thinkernel/gerrit,dwhipstock/gerrit,anminhsu/gerrit,Distrotech/gerrit,Overruler/gerrit,joshuawilson/merrit,anminhsu/gerrit,MerritCR/merrit,WANdisco/gerrit,quyixia/gerrit,thesamet/gerrit,renchaorevee/gerrit,MerritCR/merrit,anminhsu/gerrit,thinkernel/gerrit,Seinlin/gerrit,dwhipstock/gerrit,jackminicloud/test,netroby/gerrit,gerrit-review/gerrit,netroby/gerrit,gerrit-review/gerrit,jackminicloud/test,Seinlin/gerrit,WANdisco/gerrit,supriyantomaftuh/gerrit,gcoders/gerrit,MerritCR/merrit,Distrotech/gerrit,qtproject/qtqa-gerrit,joshuawilson/merrit,quyixia/gerrit,netroby/gerrit,hdost/gerrit,gcoders/gerrit,qtproject/qtqa-gerrit,hdost/gerrit,GerritCodeReview/gerrit,dwhipstock/gerrit,MerritCR/merrit,GerritCodeReview/gerrit,WANdisco/gerrit,hdost/gerrit,anminhsu/gerrit,thinkernel/gerrit,pkdevbox/gerrit,WANdisco/gerrit,anminhsu/gerrit,GerritCodeReview/gerrit