reorganize comments for shim's classification

src/shims/foreign_items/posix.rs

@@ -104,6 +104,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
             }
 
+            // Other shims
             "posix_memalign" => {
                 let ret = this.deref_operand(args[0])?;
                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;

src/shims/foreign_items/posix/linux.rs

@@ -40,6 +40,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
             }
 
+            // Other shims
             "pthread_getattr_np" => {
                 this.write_null(dest)?;
             }

src/shims/foreign_items/posix/macos.rs

@@ -55,7 +55,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
             }
 
-            // macOS API stubs.
+            // Other shims
             "pthread_attr_get_np" => {
                 this.write_null(dest)?;
             }

src/shims/foreign_items/windows.rs

@@ -16,6 +16,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let tcx = &{ this.tcx.tcx };
 
         match link_name {
+            // Windows API stubs.
+            // HANDLE = isize
+            // DWORD = ULONG = u32
+            // BOOL = i32
+
             // Environment related shims
             "GetEnvironmentVariableW" => {
                 // args[0] : LPCWSTR lpName (32-bit ptr to a const string of 16-bit Unicode chars)
@@ -70,10 +75,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     dest,
                 )?;
             }
-            // Windows API stubs.
-            // HANDLE = isize
-            // DWORD = ULONG = u32
-            // BOOL = i32
+
+            // Other shims
             "GetProcessHeap" => {
                 // Just fake a HANDLE
                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;