CI: Removes MinGW from cache

[am11]

• Repo: Adds VS files to .gitignore.

[am11]

Before: https://ci.appveyor.com/project/sass/libsass/build/1.0.284/job/wtrhkkvd6qsux1s0#L445

After: https://ci.appveyor.com/project/sass/libsass/build/1.0.289/job/yr73xv4n09upjp6m#L446

[coveralls]

Coverage remained the same at 80.72% when pulling 8a62662 on am11:master into dea27e5 on sass:master.

[mgreter]

LGTM and CI seems to agree 😄

[xzyfer]

LGTM! also...

28 min 53 sec
😭

[coveralls]

Coverage remained the same at 80.72% when pulling 7e2802f on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 7e2802f on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 409cc12 on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 409cc12 on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 63ab83f on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 11bbb66 on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 11bbb66 on am11:master into dea27e5 on sass:master.

[coveralls]

Coverage remained the same at 80.72% when pulling 76b5ef7 on am11:master into dea27e5 on sass:master.

[am11]

I have changed the title of this issue. The debug failure syndrome was back.

But the rest of the changes will boost the performance from ~6 mins to ~2 mins per build.

@xzyfer, please merge it so all future commits get compiled quickly (the MinGW jobs). :)

[am11]

@mgreter, that comment suggests that there were assertion errors when running the sassc command. Can you tell how did you diagnose it? I couldn't find it in the output. Is there a (hidden) verbose switch in sassc?

[xzyfer]

😍 😍 😍

[xzyfer]

Is this ready to go @am11 ?

[am11]

Yes @xzyfer! Debug can wait. :)

[xzyfer]

💥 great work!

[mgreter]

@am11 it simply did not complete the spec tests in debug mode, so I simply switched that off! Seems like we have fixed it in the mean time and you were the first one to stumble up on it!

[am11]

@mgreter, it was working when I opened this PR and now it starting to fail again: https://ci.appveyor.com/project/sass/libsass/build/1.0.303, so I reverted back that line with echo prefix. I don't know why it was working before and why failing now. But the comment there suggests that it fails with assertion failure, on running tests with debug configuration.

Perhaps, get some verbose output from sassc to check where the Debug build goes all mute for hours.