Merge branch 'selftests-bpf-implement-setting-global-variables-in-veristat'

Mykyta Yatsenko says:

====================
selftests/bpf: implement setting global variables in veristat

From: Mykyta Yatsenko <yatsenko@meta.com>

To better verify some complex BPF programs by veristat, it would be useful
to preset global variables. This patch set implements this functionality
and introduces tests for veristat.

v4->v5
  * Rework parsing to use sscanf for integers
  * Addressing nits

v3->v4:
  * Fixing bug in set_global_var introduced by refactoring in previous patch set
  * Addressed nits from Eduard

v2->v3:
  * Reworked parsing of the presets, using sscanf to split into variable and
  value, but still use strtoll/strtoull to support range checks when parsing
  integers
  * Fix test failures for no_alu32 & cpuv4 by checking if veristat binary is in
  parent folder
  * Introduce __CHECK_STR macro for simplifying checks in test
  * Modify tests into sub-tests
====================

Link: https://patch.msgid.link/20250225163101.121043-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>