[CPU] Fix breakpoint host_address() to_hex_string portability

Cast uintptr_t to uint64_t explicitly for to_hex_string, which
has no uintptr_t overload and can be ambiguous on some platforms.

src/xenia/cpu/breakpoint.cc

@@ -48,7 +48,8 @@ std::string Breakpoint::to_string() const {
     str += " " + functions[0]->name();
     return str;
   } else {
-    return std::string("x64 ") + xe::string_util::to_hex_string(host_address());
+    return std::string("x64 ") + xe::string_util::to_hex_string(
+                                     static_cast<uint64_t>(host_address()));
   }
 }