travis: install dwz package on linux tests
travis: install dwz package on linux tests

aarzilli/delve,go-delve/delve,aarzilli/delve,dr2chase/delve,alexbrainman/delve,aarzilli/delve,alexbrainman/delve,dr2chase/delve,aarzilli/delve,go-delve/delve,dr2chase/delve,alexbrainman/delve,derekparker/delve,go-delve/delve,go-delve/delve,derekparker/delve,go-delve/delve,derekparker/delve