This doesn't fix the alignment issue yet.

See https://bugs.llvm.org/show_bug.cgi?id=35928 and
https://reviews.llvm.org/D42233.

Like Patcheng's https://reviews.llvm.org/D42233 but for Custom Sections instead

padding for the padding gods.

Also try hard to extract a symbol from a MCExpr when writing relocations

I doubt this is the right way, but hey it emits an object now

I actually do need to know what's breaking.

Swift uses aliased symbols to refer to offsets within metadata structures.

eg

```
@"$s12SwiftPrivate28_stdlib_ShardedAtomicCounterVN" = alias %swift.type, bitcast (i32* getelementptr inbounds (<{ i8**, i32, <{ i32, i32, i32, i32, i32, i32, i32 }>*, i32, i32 }>, <{ i8**, i32, <{ i32, i32, i32, i32, i32, i32, i32 }>*, i32, i32 }>* @"$s12SwiftPrivate28_stdlib_ShardedAtomicCounterVMf", i32 0, i32 1) to %swift.type*)
```

My previous commit only got the alias to refer to the correct target symbol,
but not at the right offset.

This commit properly emits these symbols.

With this change, print("hello world") works but print() with anything else is still broken.

Don't need the logging anymore

This reverts commit 8b8f31f.