Merge branch 'fixes-for-stack-with-allow_ptr_leaks'

Kumar Kartikeya Dwivedi says:

====================
Fixes for stack with allow_ptr_leaks

Two fixes for usability/correctness gaps when interacting with the stack
without CAP_PERFMON (i.e. with allow_ptr_leaks = false). See the commits
for details. I've verified that the tests fail when run without the fixes.

Changelog:
----------
v3 -> v4
v3: https://lore.kernel.org/bpf/20241202083814.1888784-1-memxor@gmail.com

 * Address Andrii's comments
   * Fix bug paperered over by missing CAP_NET_ADMIN in verifier_mtu
     test
   * Add warning when undefined CAP_ constant is specified, and fail
     test
   * Reorder annotations to be more clear
   * Verify that fixes fail without patches again
 * Add Acked-by from Andrii

v2 -> v3
v2: https://lore.kernel.org/bpf/20241127212026.3580542-1-memxor@gmail.com

 * Address comments from Eduard
   * Fix comment for mark_stack_slot_misc
   * We can simply always return early when stype == STACK_INVALID
   * Drop allow_ptr_leaks conditionals
   * Add Eduard's __caps_unpriv patch into the series
   * Convert test_verifier_mtu to use it
   * Move existing tests to __caps_unpriv annotation and verifier_spill_fill.c
   * Add Acked-by from Eduard

v1 -> v2
v1: https://lore.kernel.org/bpf/20241127185135.2753982-1-memxor@gmail.com

 * Fix CI errors in selftest by removing dependence on BPF_ST
====================

Link: https://patch.msgid.link/20241204044757.1483141-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>