Add gcc and musl-dev to dev Dockerfile

[seemethere]

Needed to be able to do make -f docker.Makefile binary on multiple
architectures.

Signed-off-by: Eli Uriegas eli.uriegas@docker.com

- What I did
Fixed make -f docker.Makefile binary on aarch64, would fail before with:

Step 4/11 : RUN     go get -d github.com/LK4D4/vndr &&         cd /go/src/github.com/LK4D4/vndr &&         git checkout -q "$VNDR_SHA" &&         go build -v -o /usr/bin/vndr . &&         rm -rf /go/src/* /go/pkg/* /go/bin/*
 ---> Running in bffec54b704f
github.com/LK4D4/vndr/godl/singleflight
github.com/LK4D4/vndr/build
github.com/LK4D4/vndr/godl
github.com/LK4D4/vndr
# github.com/LK4D4/vndr
/usr/local/go/pkg/tool/linux_arm64/link: running gcc failed: exec: "gcc": executable file not found in $PATH

The command '/bin/sh -c go get -d github.com/LK4D4/vndr &&         cd /go/src/github.com/LK4D4/vndr &&         git checkout -q "$VNDR_SHA" &&         go build -v -o /usr/bin/vndr . &&         rm -rf /go/src/* /go/pkg/* /go/bin/*' returned a non-zero code: 2
docker.Makefile:18: recipe for target 'build_docker_image' failed
make: *** [build_docker_image] Error 2

- How I did it

• Added gcc and musl-dev to the Dockerfile.dev

- How to verify it

• Running make -f docker.Makefile binary on aarch64

- Description for the changelog

* Added `gcc` and `musl-dev` to the `Dockerfile.dev`

- A picture of a cute animal (not mandatory but encouraged)

[codecov-io]

Codecov Report

Merging #767 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #767   +/-   ##
=======================================
  Coverage   53.46%   53.46%           
=======================================
  Files         218      218           
  Lines       14642    14642           
=======================================
  Hits         7829     7829           
  Misses       6327     6327           
  Partials      486      486

[dnephin]

Can we just use Dockerfile.cross dockerfile instead?

If not, can we go with this solution: #183 (comment)

[seemethere]

The base is multi arch already. There's just 2 extra dependencies to add for compiling on different architectures.

[arm64b]

IMO we need this RP to build a docker image natively on AArch64 while not use a cross solution, or can we add those 2 extra dependencies into the upstream golang:1.9.2-alpine3.6? /cc @dnephin

[dnephin]

See #816 for another solution