Migrating code to object (from faerie) (#1848)

* Using the "object" library everywhere in wasmtime.
* scroll_derive

crates/obj/src/table.rs

@@ -1,17 +1,29 @@
 use anyhow::Result;
-use faerie::{Artifact, Decl};
+use object::write::{Object, StandardSection, Symbol, SymbolSection};
+use object::{SymbolFlags, SymbolKind, SymbolScope};
 
 /// Declares data segment symbol
-pub fn declare_table(obj: &mut Artifact, index: usize) -> Result<()> {
+pub fn declare_table(obj: &mut Object, index: usize) -> Result<()> {
     let name = format!("_table_{}", index);
-    obj.declare(name, Decl::data())?;
+    let _symbol_id = obj.add_symbol(Symbol {
+        name: name.as_bytes().to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    });
     Ok(())
 }
 
 /// Emit segment data and initialization location
-pub fn emit_table(obj: &mut Artifact, index: usize) -> Result<()> {
+pub fn emit_table(obj: &mut Object, index: usize) -> Result<()> {
     let name = format!("_table_{}", index);
+    let symbol_id = obj.symbol_id(name.as_bytes()).unwrap();
+    let section_id = obj.section_id(StandardSection::Data);
     // FIXME: We need to initialize table using function symbols
-    obj.define(name, Vec::new())?;
+    obj.add_symbol_data(symbol_id, section_id, &[], 1);
     Ok(())
 }