cranelift codegen: pass source locations with external relocations;

crates/lightbeam/src/backend.rs

@@ -5404,6 +5404,8 @@ impl<'this, M: ModuleContext> Context<'this, M> {
                     .unwrap()
                     .0) as u32
                 + 2,
+            // Passing a default location here, since until proven otherwise, it's not used.
+            ir::SourceLoc::default(),
             binemit::Reloc::Abs8,
             name,
             0,

crates/lightbeam/src/translate_sections.rs

@@ -87,6 +87,7 @@ impl binemit::RelocSink for UnimplementedRelocSink {
     fn reloc_external(
         &mut self,
         _: binemit::CodeOffset,
+        _: ir::SourceLoc,
         _: binemit::Reloc,
         _: &ir::ExternalName,
         _: binemit::Addend,