The bug report describes an issue where the wrong `libtool` is used during the configuration process on Darwin/OS X, leading to build failures for `libcacard` that QEMU relies on. The user suggests modifying the configure script to check for the correct `libtool` when running on Darwin.

To classify this issue:

- **Instruction**: This relates to a faulty instruction or step in the build process.
- **Syscall**: Not applicable, as it's not related to system calls.
- **Runtime**: Not applicable, since the error occurs during configuration, not runtime execution.

The problem arises because the wrong `libtool` is used during configuration, which is part of the build instructions. Therefore, this bug falls under the **instruction** category.

**Answer:** instruction