Produce a static dlv binary to work on alpine and glibc

[briandealwis]

Following a tip from @dgageot, compile dlv as a static binary. Verified that the binary is able to be used both from alpine images and from glibc images, and even from the busybox image which has no shared libraries at all.

(Note: the path where the dlv path is copied from is changed as we're using go build rather than go install; the install didn't seem necessary.)

Fixes #30

[loosebazooka]

So this links dynamically to the library on the host container? oh the opposite, it includes everything it needs, opop

[briandealwis]

No dynamic linkage @loosebazooka — it's a static binary.