v.io/x/devtools: Do not clone Mojo recursively
v.io/x/devtools: Do not clone Mojo recursively

As title. While there may be better solutions, this...
Closes https://github.com/vanadium/issues/issues/1045

MultiPart: 1/2
Change-Id: Id72d3a534d7280a685e1735d3de8059c0b9d491e

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools