libbpf: Fix logic for finding matching program for CO-RE relocation

Fix the bug in bpf_object__relocate_core() which can lead to finding
invalid matching BPF program when processing CO-RE relocation. IF
matching program is not found, last encountered program will be assumed
to be correct program and thus error detection won't detect the problem.

Fixes: 9c82a63c ("libbpf: Fix CO-RE relocs against .text section")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220426004511.2691730-4-andrii@kernel.org