Rename "Stackmap" to "StackMap"

And "stackmap" to "stack_map".

This commit is purely mechanical.

crates/environ/src/compilation.rs

@@ -76,7 +76,7 @@ pub struct StackMapInformation {
     pub code_offset: binemit::CodeOffset,
 
     /// The stack map for identifying live GC refs at the GC safepoint.
-    pub stack_map: binemit::Stackmap,
+    pub stack_map: binemit::StackMap,
 }
 
 /// An error while compiling WebAssembly to machine code.

crates/environ/src/cranelift.rs

@@ -208,8 +208,8 @@ struct StackMapSink {
     infos: Vec<StackMapInformation>,
 }
 
-impl binemit::StackmapSink for StackMapSink {
-    fn add_stackmap(&mut self, code_offset: binemit::CodeOffset, stack_map: binemit::Stackmap) {
+impl binemit::StackMapSink for StackMapSink {
+    fn add_stack_map(&mut self, code_offset: binemit::CodeOffset, stack_map: binemit::StackMap) {
         self.infos.push(StackMapInformation {
             code_offset,
             stack_map,

crates/environ/src/data_structures.rs

@@ -1,7 +1,7 @@
 #![doc(hidden)]
 
 pub mod ir {
-    pub use cranelift_codegen::binemit::{Reloc, Stackmap};
+    pub use cranelift_codegen::binemit::{Reloc, StackMap};
     pub use cranelift_codegen::ir::{
         types, AbiParam, ArgumentPurpose, JumpTableOffsets, LibCall, Signature, SourceLoc,
         StackSlots, TrapCode, Type, ValueLabel, ValueLoc,