Bug#962228: grub-pc: Backport LUKS2 support

[Petr Vorel]

Package: grub-pc
Version: 2.04-7
Followup-For: Bug #962228

Hi,

after checking upstream git and mailing list, we should close this.

First, 2.06 feature freeze and RC1 was planned since mid of March,
I hope the upstream manages to do it before end of June. But Grub is
often late when freeze and there is still active discussion about several
fixes, including LUKS2.

LUKS2 is requires to backport more commits, as LUKS2 implementation requires
json (added in several commits). IMHO at least these commits would be needed:

c543d6781 luks2: Propagate error when reading area key fails
e933feb57 json: Get rid of casts for "jsmntok_t"
3b81607b5 json: Update jsmn library to upstream commit 053d3cd
9404c4195 luks2: Add missing newline to debug message
365e0cc3e disk: Implement support for LUKS2
dd3f49b10 luks: Move configuration of ciphers into cryptodisk
5324c335b afsplitter: Move into its own module
9fbdec2f6 bootstrap: Add gnulib's base64 module
c6a84545a json: Implement wrapping interface
528938d50 json: Import upstream jsmn-1.1.0

Kind regards,
Petr