build: Unify flags

[jschwe]

Refactor cc_flags() to return Vec, so that we can also add dynamic flags here.
This makes it easier to keep the flags in sync across bindings and compilation

[jschwe]

@sagudev What do you think about this? It seems that the flags we set diverge somewhat between bindings and build(), so I would like to put as much as possible in cc_flags.
There is more that could be moved into the function, but I first wanted to hear a general opinion before i spend more time.

[sagudev]

@sagudev What do you think about this? It seems that the flags we set diverge somewhat between bindings and build(), so I would like to put as much as possible in cc_flags. There is more that could be moved into the function, but I first wanted to hear a general opinion before i spend more time.

I would love that. I think I already tried that in the past but hit roadblocks, hopefully you will succeed.

BTW there was also issue in bindgen I think about reusing clang ran for compilation and analysis so that would be especially interesting (although maybe more for mozangle where we do full compilation using cc-rs), but still.

[jschwe]

BTW there was also issue in bindgen I think about reusing clang ran for compilation and analysis so that would be especially interesting (although maybe more for mozangle where we do full compilation using cc-rs), but still.

Thats an interesting thought! I found the issue and opened rust-lang/cc-rs#1614, since the suggestion to add an export flag feature to the cc-rs build does seem like a great idea, if upstream accepts it.