Removes duplicate code in src/obj.rs, crates/obj and crates/jit/object.rs (#1993)

Changes:

 -  Moves object creation code from crates/jit/object.rs to the creates/obj (as ObjectBuilder)
 -   Removes legacy crates/obj/function.rs
 -  Removes write_debugsections

crates/debug/src/write_debuginfo.rs

@@ -2,8 +2,10 @@ pub use crate::read_debuginfo::{read_debuginfo, DebugInfoData, WasmFileInfo};
 pub use crate::transform::transform_dwarf;
 use gimli::write::{Address, Dwarf, EndianVec, FrameTable, Result, Sections, Writer};
 use gimli::{RunTimeEndian, SectionId};
+use wasmtime_environ::entity::{EntityRef, PrimaryMap};
 use wasmtime_environ::isa::{unwind::UnwindInfo, TargetIsa};
-use wasmtime_environ::{Compilation, ModuleAddressMap, ModuleVmctxInfo, ValueLabelsRanges};
+use wasmtime_environ::wasm::DefinedFuncIndex;
+use wasmtime_environ::{ModuleAddressMap, ModuleVmctxInfo, ValueLabelsRanges};
 
 #[derive(Clone)]
 pub enum DwarfSectionRelocTarget {
@@ -130,18 +132,18 @@ impl Writer for WriterRelocate {
 
 fn create_frame_table<'a>(
     isa: &dyn TargetIsa,
-    infos: impl Iterator<Item = &'a Option<UnwindInfo>>,
+    infos: &PrimaryMap<DefinedFuncIndex, &Option<UnwindInfo>>,
 ) -> Option<FrameTable> {
     let mut table = FrameTable::default();
 
     let cie_id = table.add_cie(isa.create_systemv_cie()?);
 
-    for (i, info) in infos.enumerate() {
+    for (i, info) in infos {
         if let Some(UnwindInfo::SystemV(info)) = info {
             table.add_fde(
                 cie_id,
                 info.to_fde(Address::Symbol {
-                    symbol: i,
+                    symbol: i.index(),
                     addend: 0,
                 }),
             );
@@ -151,16 +153,16 @@ fn create_frame_table<'a>(
     Some(table)
 }
 
-pub fn emit_dwarf(
+pub fn emit_dwarf<'a>(
     isa: &dyn TargetIsa,
     debuginfo_data: &DebugInfoData,
     at: &ModuleAddressMap,
     vmctx_info: &ModuleVmctxInfo,
     ranges: &ValueLabelsRanges,
-    compilation: &Compilation,
+    unwind_info: &PrimaryMap<DefinedFuncIndex, &Option<UnwindInfo>>,
 ) -> anyhow::Result<Vec<DwarfSection>> {
     let dwarf = transform_dwarf(isa, debuginfo_data, at, vmctx_info, ranges)?;
-    let frame_table = create_frame_table(isa, compilation.into_iter().map(|f| &f.unwind_info));
+    let frame_table = create_frame_table(isa, unwind_info);
     let sections = emit_dwarf_sections(dwarf, frame_table)?;
     Ok(sections)
 }