Merge branch 'Add support of pointer to struct in global'

Dmitrii Banshchikov says:

====================

This patchset adds support of pointers to type with known size among
global function arguments.

The motivation is to overcome the limit on the maximum number of allowed
arguments and avoid tricky and unoptimal ways of passing arguments.

A referenced type may contain pointers but access via such pointers
cannot be veirified currently.

v2 -> v3
 - Fix reg ID generation
 - Fix commit description
 - Fix typo
 - Fix tests

v1 -> v2:
 - Allow pointer to any type with known size rather than struct only
 - Allow pointer in global functions only
 - Add more tests
 - Fix wrapping and v1 comments
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>