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/environ/src/lib.rs

@@ -87,3 +87,28 @@ pub(crate) fn reference_type(
         _ => panic!("unsupported Wasm reference type"),
     }
 }
+
+/// Iterates through all `LibCall` members and all runtime exported functions.
+#[macro_export]
+macro_rules! for_each_libcall {
+    ($op:ident) => {
+        $op![
+            (UdivI64, wasmtime_i64_udiv),
+            (UdivI64, wasmtime_i64_udiv),
+            (SdivI64, wasmtime_i64_sdiv),
+            (UremI64, wasmtime_i64_urem),
+            (SremI64, wasmtime_i64_srem),
+            (IshlI64, wasmtime_i64_ishl),
+            (UshrI64, wasmtime_i64_ushr),
+            (SshrI64, wasmtime_i64_sshr),
+            (CeilF32, wasmtime_f32_ceil),
+            (FloorF32, wasmtime_f32_floor),
+            (TruncF32, wasmtime_f32_trunc),
+            (NearestF32, wasmtime_f32_nearest),
+            (CeilF64, wasmtime_f64_ceil),
+            (FloorF64, wasmtime_f64_floor),
+            (TruncF64, wasmtime_f64_trunc),
+            (NearestF64, wasmtime_f64_nearest)
+        ];
+    };
+}