Prevent frontend function confusion (#383)

Function symbols can clash as we compile multiple YUL `object`
definition into the same `LLVM` module.
- Disambiguate via unique function symbols based its location (runtime
or deploy code).
- Use `LinkOnceODR` linkage for compiler builtin helpers.

---------

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

crates/llvm-context/src/polkavm/evm/immutable.rs

@@ -210,7 +210,7 @@ pub fn load<'ctx>(
             let name = <Load as RuntimeFunction>::NAME;
             context.build_call(
                 context
-                    .get_function(name)
+                    .get_function(name, false)
                     .expect("is always declared for runtime code")
                     .borrow()
                     .declaration(),