Enable Mach-O on iOS in gimli. (#378)

* Enable Mach-O on iOS in gimli.

* Enable Mach-O on tvOS and watchOS in gimli.

Author: cutsoy

src/symbolize/gimli.rs

@@ -201,7 +201,12 @@ cfg_if::cfg_if! {
                 }],
             })
         }
-    } else if #[cfg(target_os = "macos")] {
+    } else if #[cfg(any(
+        target_os = "macos",
+        target_os = "ios",
+        target_os = "tvos",
+        target_os = "watchos",
+    ))] {
         // macOS uses the Mach-O file format and uses DYLD-specific APIs to
         // load a list of native libraries that are part of the appplication.