Description

In 0.16.1, IDEA support does not get enabled despite Botan supporting it

Steps to Reproduce

1. Run cmake -S rnp-0.16.1 -B build
2. Build: cd build && make
3. Execute the built "rnpkeys" binary without any arguments: ./src/rnpkeys/rnpkeys

Expected Behavior

The "Encryption" line should include "IDEA" in its list

Actual Behavior

IDEA does not appear in the "Encryption" line:
Encryption: TRIPLEDES, CAST5, BLOWFISH, AES128, AES192, AES256, TWOFISH, CAMELLIA128, CAMELLIA192, CAMELLIA256, SM4

Adding #cmakedefine ENABLE_IDEA to be src/lib/config.h.in fixes the issue.