undo Xcode 13 GM workaround which leads to miscompiles in Xcode 16.4

[weissi]

Motivation:

Xcode 13 is really quite old (3 major releases and it was the GM release anyway) and this workaround can cause other issues. This workaround also causes the Xcode 16.4 Swift compiler in release mode to miscompile @usableFromInline let sysFree: @convention(c) [...] = { free($0) } into a CPU spin loop.

Modifications:

• Remove the Xcode 13 GM workaround.
• Remove the possibility of this line being miscompiled.

Result:

Better, possibly faster code and fewer chance of hitting bugs.

[weissi]

oha, this actually trigger a compiler crash :|

[weissi]

oha, this actually trigger a compiler crash :|

worked around the compiler crash.

[Lukasa]

@weissi The formatter wants you to remove -> Void from your function declaration. As you're working around a compiler crash, I don't want to just unilaterally make that change for you without you reproducing whether the compiler continues not to crash with this spelling.