bpf: name unnamed bpf programs

bpf-firewall and bpf-devices do not have names. This complicates
debugging with bpftool(8).

Assign names starting with 'sd_' prefix:
* firewall program names are 'sd_fw_ingress' for ingress attach
point and 'sd_fw_egress' for egress.
* 'sd_devices' for devices prog

'sd_' prefix is already used in source-compiled programs, e.g.
sd_restrictif_i, sd_restrictif_e, sd_bind6.

The name must not be longer than 15 characters or BPF_OBJ_NAME_LEN - 1.

Assign names only to programs loaded to kernel by systemd since
programs pinned to bpffs are already loaded.

src/shared/bpf-program.h

@@ -20,6 +20,7 @@ struct BPFProgram {
         /* The loaded BPF program, if loaded */
         int kernel_fd;
         uint32_t prog_type;
+        char *prog_name;
 
         /* The code of it BPF program, if known */
         size_t n_instructions;
@@ -32,7 +33,7 @@ struct BPFProgram {
         uint32_t attached_flags;
 };
 
-int bpf_program_new(uint32_t prog_type, BPFProgram **ret);
+int bpf_program_new(uint32_t prog_type, const char *prog_name, BPFProgram **ret);
 int bpf_program_new_from_bpffs_path(const char *path, BPFProgram **ret);
 BPFProgram *bpf_program_free(BPFProgram *p);