Do not disable cgo (rm CGO_ENABLED=0)

[chrismwendt]

You can disable it with env CGO_ENABLED=0 lsif-go if necessary.

Fixes https://github.com/sourcegraph/sourcegraph/issues/33285

Might fix https://github.com/sourcegraph/sourcegraph/pull/30307#issuecomment-1041917665. I was unable to repro the error, but I was able to determine that binding.go is now included in the output whereas before this change it wasn't.

Might fix https://github.com/sourcegraph/lsif-go/issues/227 for the same reason.

I didn't notice any negative consequences of this change:

• gorillla/mux still works
• sourcegraph/src-cli still works
• sourcegraph/sourcegraph/lib still works without the workaround. Olaf had an issue but I was unable to repro.
• google/gvisor (with C files) still doesn't work due to having .c files in Go packages without import "C"
• gonum/gonum (with assembly files) still works, same set of files ended up in the LSIF dump
• A fresh repo with https://riptutorial.com/go/example/21315/cgo--first-steps-tutorial emits more info than before this change

[varungandhi-src]

Could you elaborate on how this fixes https://github.com/sourcegraph/sourcegraph/issues/33285?