CI for Mac is broken

[tarcv]

CI for Mac is broken

Apparently that -lc++fs flag I removed a few commits back fixes this issue, according to this question on Stack Overflow

[TarCV]

Mac OS is a weird platform in terms of building C/C++ programs. CLang/LLVM that comes with Mac OS/XCode is old, so I install a newer one with homebrew. Probably it's just CLang picking wrong standard library implementation or may be CLang package in homebrew is just old.

It uses version 9 (Ubuntu has version 10 and compiles normally), it just isn't shipped with the standard libraries apparently.

Edit: just compiled with clang 9 on Ubuntu. Mac OS' clang definitely doesn't come with the entire standards library.

[TarCV]

From https://formulae.brew.sh/formula/llvm it looks like LDFLAGS were changed. So may be updating them will fix CI, I'll try it later.

[TarCV]

That didn't help. And apparently XCode 11 is not enough too.
https://dev.azure.com/tarcv/botc/_build/results?buildId=115&view=logs&j=a4f1cc8a-0ccb-5e90-36f4-f06f41d0ce59&t=ca6b548a-c0fd-5f27-176c-c59ec27fafde