Bugfix: ParseCFlagsFromMakeOutput was never being called

[hugomg]

Previously, the make output was never being parsed, even when the
c_parse_makefile option was set. I think this is because of a bug in GetCFlags, which would only try parsing the makefile if the compile_commands.json was ALSO present.

I'm not sure if I need to add tests for this, because it's a small change. If it is then I can come back later to add those.

[hsanson]

I am not familiar with this part of ALE but the fact that there are many tests for Makefile flags parsing (see test_c_flag_parsing.vader) and they were passing before this fix makes me suspect something is wrong. I would recommend to check the tests and see why they worked before and after this fix.

[hugomg]

On the matter of test_c_flag_parsing, my impression is that the tests that we have are unit tests to see if the ParseCFlagsFromMakeOutput function does the right thing. However, the bug that I found was that ParseCFlagsFromMakeOutput wasn't being called in the first place...

It's possible that there really are no tests that could have caught this. I might be missing something but I can't find any tests that call ale_linters#c#cc#GetCommand or ale#c#GetCFlags.

By the way, according to the git log the commit that introduced the contentious if statement appears to be this one: affeed7

[hsanson]

I would recommend this PR be reviewed by @w0rp.

[w0rp]

Yeah, this is just a mistake I made. I wouldn't worry about unit testing every single thing in the universe, I'll just merge this.

[w0rp]

Cheers! 🍻