Remove OS check for Darwin and Sparc during mirror creation in gpdemo.
Remove OS check for Darwin and Sparc during mirror creation in gpdemo.

Currently, gpdemo does not build mirrors for Darwin and Sparc. This was a
restriction from the early 2010s and should not be an issue today with
modern systems.

ashwinstar/gpdb,chrishajas/gpdb,CraigHarris/gpdb,yuanzhao/gpdb,royc1/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,janebeckman/gpdb,adam8157/gpdb,50wu/gpdb,Chibin/gpdb,Chibin/gpdb,xinzweb/gpdb,kaknikhil/gpdb,ahachete/gpdb,edespino/gpdb,ahachete/gpdb,xuegang/gpdb,royc1/gpdb,xuegang/gpdb,ahachete/gpdb,jmcatamney/gpdb,Quikling/gpdb,janebeckman/gpdb,rvs/gpdb,CraigHarris/gpdb,edespino/gpdb,janebeckman/gpdb,adam8157/gpdb,adam8157/gpdb,yuanzhao/gpdb,royc1/gpdb,lintzc/gpdb,lintzc/gpdb,greenplum-db/gpdb,edespino/gpdb,cjcjameson/gpdb,lintzc/gpdb,royc1/gpdb,yuanzhao/gpdb,chrishajas/gpdb,yuanzhao/gpdb,ahachete/gpdb,yuanzhao/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,50wu/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,Quikling/gpdb,adam8157/gpdb,lintzc/gpdb,xuegang/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,ahachete/gpdb,adam8157/gpdb,janebeckman/gpdb,janebeckman/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,rvs/gpdb,0x0FFF/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,xinzweb/gpdb,kaknikhil/gpdb,lisakowen/gpdb,CraigHarris/gpdb,cjcjameson/gpdb,lintzc/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,xuegang/gpdb,edespino/gpdb,rvs/gpdb,edespino/gpdb,xuegang/gpdb,janebeckman/gpdb,Quikling/gpdb,lintzc/gpdb,lisakowen/gpdb,Quikling/gpdb,chrishajas/gpdb,ahachete/gpdb,50wu/gpdb,ashwinstar/gpdb,lisakowen/gpdb,janebeckman/gpdb,rvs/gpdb,lisakowen/gpdb,Quikling/gpdb,greenplum-db/gpdb,Chibin/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,Quikling/gpdb,kaknikhil/gpdb,lisakowen/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,royc1/gpdb,chrishajas/gpdb,0x0FFF/gpdb,CraigHarris/gpdb,xinzweb/gpdb,Chibin/gpdb,xinzweb/gpdb,cjcjameson/gpdb,rvs/gpdb,Quikling/gpdb,lintzc/gpdb,Chibin/gpdb,xuegang/gpdb,Chibin/gpdb,CraigHarris/gpdb,adam8157/gpdb,rvs/gpdb,cjcjameson/gpdb,Chibin/gpdb,edespino/gpdb,50wu/gpdb,edespino/gpdb,Quikling/gpdb,ashwinstar/gpdb,Quikling/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,edespino/gpdb,yuanzhao/gpdb,rvs/gpdb,xinzweb/gpdb,royc1/gpdb,chrishajas/gpdb,50wu/gpdb,jmcatamney/gpdb,xinzweb/gpdb,janebeckman/gpdb,ahachete/gpdb,ahachete/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,lisakowen/gpdb,royc1/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,Quikling/gpdb,janebeckman/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,chrishajas/gpdb,xuegang/gpdb,lisakowen/gpdb,xuegang/gpdb,cjcjameson/gpdb,chrishajas/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,Chibin/gpdb,CraigHarris/gpdb,lisakowen/gpdb,edespino/gpdb,xinzweb/gpdb,janebeckman/gpdb,Chibin/gpdb,xuegang/gpdb,50wu/gpdb,chrishajas/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,rvs/gpdb,0x0FFF/gpdb,royc1/gpdb,cjcjameson/gpdb,lintzc/gpdb,adam8157/gpdb,rvs/gpdb,Chibin/gpdb,xinzweb/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,lintzc/gpdb,cjcjameson/gpdb,rvs/gpdb,edespino/gpdb