enable use of buildcache when running synth-ip.tcl
enable use of buildcache when running synth-ip.tcl

Change-Id: I2b87c76ceac87f153b7e8b67f8a7d9bd49b5c985

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