Move trap information to a section of the compiled image (#3241)

This commit moves the `traps` field of `FunctionInfo` into a section of
the compiled artifact produced by Cranelift. This section is quite large
and when previously encoded/decoded with `bincode` this can take quite
some time to process. Traps are expected to be relatively rare and it's
not necessarily the right tradeoff to spend so much time
serializing/deserializing this data, so this commit offloads the section
into a custom-encoded binary format located elsewhere in the compiled image.

This is similar to #3240 in its goal which is to move very large pieces
of metadata to their own sections to avoid decoding anything when we
load a precompiled modules. This also has a small benefit that it's
slightly more efficient storage for the trap information too, but that's
a negligible benefit.

This is part of #3230 to make loading modules fast.

crates/cranelift/src/lib.rs

@@ -94,7 +94,9 @@ use cranelift_codegen::isa::{unwind::UnwindInfo, CallConv, TargetIsa};
 use cranelift_entity::PrimaryMap;
 use cranelift_wasm::{DefinedFuncIndex, FuncIndex, WasmFuncType, WasmType};
 use target_lexicon::CallingConvention;
-use wasmtime_environ::{FilePos, FunctionInfo, InstructionAddressMap, Module, TypeTables};
+use wasmtime_environ::{
+    FilePos, FunctionInfo, InstructionAddressMap, Module, TrapInformation, TypeTables,
+};
 
 pub use builder::builder;
 
@@ -122,6 +124,10 @@ pub struct CompiledFunction {
     /// location found in the wasm input.
     address_map: FunctionAddressMap,
 
+    /// Metadata about traps in this module, mapping code offsets to the trap
+    /// that they may cause.
+    traps: Vec<TrapInformation>,
+
     relocations: Vec<Relocation>,
     value_labels_ranges: cranelift_codegen::ValueLabelsRanges,
     stack_slots: ir::StackSlots,