Merge branch 'two-more-fixes-for-check_max_stack_depth'

Kumar Kartikeya Dwivedi says:

====================
Two more fixes for check_max_stack_depth

I noticed two more bugs while reviewing the code, description and
examples available in the patches.

One leads to incorrect subprog index to be stored in the frame stack
maintained by the function (leading to incorrect tail_call_reachable
marks, among other things).

The other problem is missing exploration pass of other async callbacks
when they are not called from the main prog. Call chains rooted at them
can thus bypass the stack limits (32 call frames * max permitted stack
depth per function).

Changelog:
----------
v1 -> v2
v1: https://lore.kernel.org/bpf/20230713003118.1327943-1-memxor@gmail.com

 * Fix commit message for patch 2 (Alexei)
====================

Link: https://lore.kernel.org/r/20230717161530.1238-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>