Fix macos support. Fix run script.

[mo10]

• Fix an extra colon when the LD_PRELOAD or DYLD_INSERT_LIBRARIES is empty Cannot run on M1 Mac (ARM games) #25
• Fix macos and linux support UnityDoorstop 4.0.0-rc.7 not working on mac #26

[ghorsington]

Thanks for the PR!

This PR still works fine from my tests with a few Linux games. I cannot, unfortunately, test macOS at the moment, but from a quick look, it seems like it was tested at least in #26. As such, I'll merge this in and have more tests later.

Thanks again!

[mo10]

I tested below platform with https://store.steampowered.com/app/1703340

1. SteamDeck (SteamOS Holo 3.3 20220803.1)
2. MacBookPro14,3, BootROM 447.80.3.0.0, 4 processors, Quad-Core Intel Core i7, 2.8 GHz, 16 GB, SMC 2.45f5
3. MacBookAir10,1, BootROM 7459.141.1, proc 8:4:4 processors, 16 GB, SMC (M1 cpu)