add IMPORT_HOST_CLOCKS support to topgen
add IMPORT_HOST_CLOCKS support to topgen

chenm001/connectal,8l/connectal,csail-csg/connectal,8l/connectal,hanw/connectal,8l/connectal,chenm001/connectal,cambridgehackers/connectal,cambridgehackers/connectal,cambridgehackers/connectal,csail-csg/connectal,hanw/connectal,8l/connectal,hanw/connectal,chenm001/connectal,chenm001/connectal,8l/connectal,cambridgehackers/connectal,csail-csg/connectal,csail-csg/connectal,csail-csg/connectal,hanw/connectal,cambridgehackers/connectal,chenm001/connectal,hanw/connectal