selftests/bpf: sync kernel headers and introduce arch support in Makefile

selftests/bpf: sync kernel headers and introduce arch support in Makefile

Synchronize the uapi kernel header files which solves the broken
uapi export of pt_regs.  Because of arch-specific uapi headers,
extended the include path in the Makefile.

With this change, the test_verifier program compiles and runs successfully
on s390.

Signed-off-by: Hendrik Brueckner <[email protected]>
Reviewed-and-tested-by: Thomas Richter <[email protected]>
Acked-by: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>