Only run dsymutil on macos.

I have this approach of bundling dsymutil. If there was
a library that handled bundling DWARF info then this wouldn't be needed.

debugvault/src/lib.rs

@@ -324,9 +324,9 @@ pub fn macho_dwarf(obj: &object::File, path: &Path) -> Result<Dwarf, dwarf::Erro
         .join(path.file_name().unwrap());
 
     if !opt_dsym.is_file() {
-        #[cfg(target_arch = "x86_64")]
+        #[cfg(all(target_arch = "x86_64", target_os = "macos"))]
         let dsymutil_path = Path::new(env!("CARGO_MANIFEST_DIR")).join("bin/dsymutil_x86_64");
-        #[cfg(target_arch = "aarch64")]
+        #[cfg(all(target_arch = "aarch64", target_os = "macos"))]
         let dsymutil_path = Path::new(env!("CARGO_MANIFEST_DIR")).join("bin/dsymutil_aarch64");
 
         if dsymutil_path.exists() {