Multi-gcc binaryBuilder update

[juan-pablo-vielma]

Updates to the multi gcc-version of binarybuilder, but does not add the symlink magic for BLAS libraries as this adds additional complexity that does not seem to be necessary (does not fix the known issues with ArchLinux).

[kalmarek]

I have a very mimimal patch for SCS.jl to enable scs-2.1.1, but currenty

• Updates to MOI v0.9 #144 drops julia-0.6,
• Enh/gpu solver #147 adds gpu solver and modifies the SCSStructs(to be merged after Updates to MOI v0.9 #144).
• Then @juan-pablo-vielma will have to update this pull (it is still scs-v2.0.2).
• Finally we release SCSBuilder with scs-v2.1.1 and
• I will provide update to for SCS.jl and v0.6 can be officially released

@juan-pablo-vielma, @blegat do we agree on this plan?

[juan-pablo-vielma]

I suggest releasing this PR as v0.5.2 (or v0.6) to have the last version with scs-v2.0.2 that runs with an up to date version of BB (this should be a simple PR whose only visible change is dropping julia 0.6). Then add #147 and scs-v2.1.1 as v0.6 (or v0.7). Maybe even the last two should be different tags (scs-v2.1.1 may require new tests for added features?)

[juan-pablo-vielma]

Ok, spoke too soon. Not sure why coverage dropped, but I imagine this PR needs #144 first.

[kalmarek]

coverage is very flaky: e.g. types.jl are still 100% covered, for sure.
If you don't like our planet, you can re-trigger the build, percentages will change ;-)

EDIT: or maybe not, as we can see ;-)

[juan-pablo-vielma]

still failing coverage. I released v2.1.1 in SCSBuilder. Tried to test it, but it seems it needs updates to SCS.jl to work.

[blegat]

It's known that coverage drops when dropping Julia v0.6 because Julia v0.6 was too generous but Julia v1.0 is not generous enough: JuliaCI/Coverage.jl#187
Adding Julia v1.1 an v1.2 might help

[juan-pablo-vielma]

Ok, v1.1 and v1.2 also passing, but there is still a drop in coverage

[blegat]

there is still a drop in coverage

Looking at the uncovered lined, it doesn't make much sense. It's out of the scope of this PR

[blegat]

@juan-pablo-vielma Can you rebase ? We need to release v0.6.0 so that SCS has a release supporting MOI v0.9. Currently JuMP examples tests are failing because of SCS

[juan-pablo-vielma]

Rebasing done.

[blegat]

LGTM, @kalmarek any objection to merge ?

[kalmarek]

@blegat not at all, I'm looking forward!