Hide certain symbols for X360 COFFs (encounter#248)

* hide except_data symbols

* hide unwinds by default

* move COFF filters to obj/read.rs

* cargo fmt read.rs

* clippy moment

* clippy pls

Author: rjkiv

objdiff-core/src/obj/read.rs

@@ -74,6 +74,14 @@ fn map_symbol(
     {
         flags |= SymbolFlag::Hidden;
     }
+    if file.format() == object::BinaryFormat::Coff
+        && let Ok(name) = symbol.name()
+        && (name.starts_with("except_data_")
+            || name.starts_with("__unwind")
+            || name.starts_with("__catch"))
+    {
+        flags |= SymbolFlag::Hidden;
+    }
 
     let kind = match symbol.kind() {
         object::SymbolKind::Text => SymbolKind::Function,