Fix clang warnings.

Review URL: http://breakpad.appspot.com/298002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@823 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/mac/MachIPC.h

@@ -139,12 +139,6 @@ class MachMsgPortDescriptor : public mach_msg_port_descriptor_t {
     return disposition;
   }
 
-  // We're just a simple wrapper for mach_msg_port_descriptor_t
-  // and have the same memory layout
-  operator mach_msg_port_descriptor_t&() {
-    return *this;
-  }
-
   // For convenience
   operator mach_port_t() const {
     return GetMachPort();