Make build-linux Target Fails

[alexanderbez]

On the latest develop (feb3acd), the make target build-linux fails with:

GOOS=linux GOARCH=amd64 /Library/Developer/CommandLineTools/usr/bin/make build
go build -tags netgo -ldflags "-X github.com/cosmos/cosmos-sdk/version.GitCommit=feb3acdb" -o build/gaiad ./cmd/gaia/cmd/gaiad
# github.com/cosmos/cosmos-sdk/vendor/github.com/zondax/ledger-goclient
vendor/github.com/zondax/ledger-goclient/ledger.go:76:18: undefined: hid.Devices
vendor/github.com/zondax/ledger-goclient/ledger.go:99:18: undefined: hid.Devices
make[1]: *** [build] Error 2
make: *** [build-linux] Error 2

As @ebuchman suggested, we should have build tags to support ledger/keybase integration. However, this is not trivial as it stands due to the way said code is structured. It'll need some minor refactoring to facilitate this.

[cwgoes]

make build-linux works fine for me; are you perchance running this on a Mac? Perhaps we need to package the HID library differently for OS X.

[alexanderbez]

@cwgoes yes, this was ran on a mac. More specifically:

ProductName:    Mac OS X
ProductVersion: 10.13.4
BuildVersion:   17E199

[ebuchman]

See #1502

I think it would be ideal if we could refactor a little bit so it's easier to toggle building things that require CGO

[ValarDragon]

Note, on a clean ubuntu server install, I get the following error with make install. CGO assumes GCC, which isn't in our installation scripts. (not sure if its in the installation readme either)

root@internal-testnet:~/goApps/src/github.com/cosmos/cosmos-sdk# make install
go install -tags netgo -ldflags "-X github.com/cosmos/cosmos-sdk/version.GitCommit=1f3ab37" ./cmd/gaia/cmd/gaiad
# github.com/cosmos/cosmos-sdk/vendor/github.com/brejski/hid
exec: "gcc": executable file not found in $PATH
Makefile:40: recipe for target 'install' failed
make: *** [install] Error 2

Agreed we need to add a build flag.

[ValarDragon]

Do we want to make the build flag here "Cgo and Ledger=True", or just have everything with cgo install the ledger. I suggest requiring both before attempting ledger installation.

[ValarDragon]

Closing in favor of #1581