Replace periods with underscores in prog/map pin paths to align with
libbpf's sanitize_pin_path() behavior. The BPF filesystem (bpffs)
disallows periods in filenames, and this change prevents pinning
errors for maps with names containing them, such as .rodata sections.
Bug: 419635765
Bug: 438637519
Test: manual, load maps names containing . from ag/35064705
Change-Id: I55dd4caf38c3ccc39bccd6ea670b647c330d6793
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>