Allow value-level encryption to be controlled by a compiler define

[matbech]

Description

Allow value-level encryption to be controlled by a compiler define. Preserve enabled default unless SQLITE3MC_ENABLE_VLE is supplied by the build.

Type of Change

Please select the type of change:

• Refactor (no behavior change)

Problem / Motivation

For Refactors:
Allow value-level encryption to be controlled by a compiler define.

Checklist

• I have independently verified the issue
• I am not submitting unverified or speculative changes
• I understand that AI-assisted changes must be reviewed by a human before submission

[utelle]

Allow value-level encryption to be controlled by a compiler define. Preserve enabled default unless SQLITE3MC_ENABLE_VLE is supplied by the build.

Actually, the unconditional #define SQLITE3MC_ENABLE_VLE 1 remained there accidentally. I simply forgot to remove it after my first experiments with the new feature. The idea was to only enable the VLE feature if it is explicitly requested.

So, it boils down to the question whether the VLE feature should be enabled by default or not.

[utelle]

I removed the unconditional define for SQLITE3MC_ENABLE_VLE. To have the feature disabled by default is the intended behaviour. And now the feature can be enabled by the user's descretion.