selftests/bpf: migrate align.c tests to test_loader framework

While working on pointer tracking changes I found it necessary to
update expected log messages in align.c series of tests.
As a preliminary step, migrate these tests to test_loader framework.

The tests in question load BPF program and check if expected log is
produced, the log is specified as:

	.matches = {
		...
		{4, "R3", "32"},
		...
	}

Where:
- '4' is an *instruction number* (contrary to the field name in
  struct bpf_reg_match).
- 'R3' is the name of the register to check.
- '32' is the value expected for this register.

Mimic the same logic using __msg macro.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>

Author: eddyz87