add columns to debug information (#362)

- Add column numbers to debug information.
- Do not build allocas at entry for now.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/llvm-context/src/polkavm/context/runtime.rs

@@ -35,6 +35,7 @@ where
             Self::r#type(context),
             0,
             Some(inkwell::module::Linkage::External),
+            None,
         )?;
 
         let mut attributes = Self::ATTRIBUTES.to_vec();