Disable optimizations for macOS builds

[Veid]

Summary

SUMMARY: Build "Disable optimizations for macOS builds"

Purpose of change

Fixes #23171

Describe the solution

Disable compiler optimizations for macOS builds.

Additional context

I believe (not sure) specific/older versions of clang appear to have a bug such that they don't copy the std::function object properly with optimization switch turned on. This is a band-aid fix that should stop the macOS builds from crashing, for now.

See:
#23171
#17898 (diff)

[ralreegorganon]

You're changing this for all macOS builds, cross-compiled and native, but it compiles natively and runs just fine on the latest releases:

clang --version
Apple LLVM version 10.0.0 (clang-1000.10.44.2)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

sw_vers
ProductName:	Mac OS X
ProductVersion:	10.14.1
BuildVersion:	18B75

make NATIVE=osx OSX_MIN=10.14 CLANG=1 CCACHE=1 LUA=1 TILES=1 RELEASE=1 -j6

Can you consider making this a bit more targeted, given you're kicking it all the way down to -O0? OSX_MIN and OSXCROSS both exist in the makefile and provide some levers to focus this a bit more.

[jfcaron3]

This needs to be reverted, I think. 10.11 is now two years past end-of-life, but with some new features enabled by default in stable, the game is very very slow and not enjoyable to play on medium Mac hardware. I can confirm that compiling the game for myself on 10.13 is actually playable.

How much more work would it be to maintain two macOS builds? One for <=10.11 and one for >10.11?