build: disable TLS heartbeat extension by default

The heartbeat extension in TLS (RFC 6520) is not widely used given other implementations dropped support for it. This makes it disabled by default, though the users are able to enable it back with the --enable-heartbeat-support configure option.

Fixes: #743 (closed)

Checklist

• Commits have Signed-off-by: with name/author being identical to the commit author
• Code modified for feature
• Test suite updated with functionality tests
• Test suite updated with negative tests
• Documentation updated / NEWS entry present (for non-trivial changes)
• CI timeout is 2h or higher (see Settings/CICD/General pipelines/Timeout)

Reviewer's checklist:

• Any issues marked for closing are addressed
• There is a test suite reasonably covering new functionality or modifications
• Function naming, parameters, return values, types, etc., are consistent and according to CONTRIBUTION.md
• This feature/change has adequate documentation added
• No obvious mistakes in the code

added 4 commits

• 2f0bf352...6d8ea338 - 3 commits from branch gnutls:master
• 3d7459d1 - build: disable TLS heartbeat extension by default

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requested review from @ZoltanFridrich

marked the checklist item No obvious mistakes in the code as completed

marked the checklist item This feature/change has adequate documentation added as completed

approved this merge request

Looks good.

enabled an automatic merge when the pipeline for 3d7459d1 succeeds

added 1 commit

• ad1231aa - .gitlab-ci.yml: ensure libtasn1-tools is installed

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mentioned in merge request !1681 (merged)

mentioned in commit 358bbdd1

merged