`hilti/runtime/include/lambda.h` is licensed under CPOL license which is not a recognized license

[bbannier]

The file hilti/runtime/include/lambda.h is licensed under the CPOL license which is not a recognized open source license according to e.g., OSI, mostly due to the restrictions it places on how the software can be used. It seems this license is incompatible with how Spicy or other Zeek software are released and could prevent users from deploying Spicy or zeek-5 in its default configuration. We should look into replacing that code.

[bbannier]

As a workaround for users wishing to install zeek-5 without pulling the offending file onto their system, building Zeek with Spicy disabled seems to work.

$ git clone https://github.com/zeek/zeek
$ cd zeek

# Remove the Spicy submodule before pulling down submodules.
# This prevents the offending file ever being on the system.
$ git rm auxil/spicy/spicy
$ git submodule update --init --recursive --depth 1

# Configure without Spicy.
$ ./configure --disable-spicy