Add config-gcc role

[Yikun]

Let's make things better!

Is your feature enhancement related to a problem? Please describe.

Current, we don't have a common role to address installation of gcc/g++

Describe the solution you'd like

  roles:
    - role: config-gcc
      gcc_version: 7

Describe alternatives you've considered

Write the gcc installation in everywhere. : (

POC:

Code: https://github.com/liu-sheng/openlab-zuul-jobs/tree/master/roles/config-gcc
Example: https://github.com/Yikun/arm-openlab-test/pull/6/files

[kiwik]

@Yikun , comment keyword is Close, not Close-issue, so this issue is not closed automatically, it's OK, let me closing it now

[Yikun]

@kiwik ok, thanks!