gitlab: Import the gitlab CI from the master branch (devel tree).
Original code written by Alexandre Julliard, RĂ©mi Bernon and
Hugh McMaster.
Changes specific for stable:
- Do not run the build script on each commit.
The build scripts are missing on the initially pulled commits.
Also it is common for the stable build to be broken until a few
commits are cherry-picked.
- Use the correct Gecko and Mono versions.
- Don't run the tests for now as too many fail.
Signed-off-by: Michael Stefaniuc <mstefani@winehq.org>