ML-DSA (Dilithium) for libgcrypt

Hello,

For 1.12, I am working to integrate ML-DSA into libgcrypt.  The ticket is:

    https://dev.gnupg.org/T7640

I created gniibe/t7640 branch for this task.  Please have a look at:

    https://dev.gnupg.org/source/libgcrypt/history/gniibe%252Ft7640/

I go through the same approach of Kyber integration into libgcrypt.

I'm going to merge the changes to master, step by step.


I wonder if use of secure memory is needed or not.  If needed, an
application should have a setting of auto expanding secure memory with
GCRYCTL_AUTO_EXPAND_SECMEM, because the size of things for PQC matters.
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