make install always downloads linux version of 'dep'

[Dentrax]

Describe the bug

$ make install

install: USE_DEP=true USE_GLIDE=
dep version || make install-dep
/bin/sh: /Users/furkan.turkal/go/bin/dep: cannot execute binary file
curl -L -s https://github.com/golang/dep/releases/download/v0.5.0/dep-linux-amd64 -o $GOPATH/bin/dep
chmod +x $GOPATH/bin/dep
dep ensure -vendor-only -v
/Users/furkan.turkal/go/bin/dep: /Users/furkan.turkal/go/bin/dep: cannot execute binary file
make: *** [install] Error 126

To Reproduce Steps to reproduce the behavior:

1. Try this on darwin architecture
2. Run $ make install
3. See the error

Expected behavior It should decide correct architecture of dep

Version (please complete the following information):

• OS: macOS
• Jaeger version: 2.29.1
• Deployment: -

What troubleshooting steps did you try? I manually set the correct architecture as following:

$ curl -L -s https://github.com/golang/dep/releases/download/v0.5.4/dep-darwin-amd64 -o $GOPATH/bin/dep
$ chmod +x $GOPATH/bin/dep
$ make install
// works

Additional context

We can implement an os & arch decider func in the Makefile.

[yurishkuro]

I install dep via brew on Mac