ddb show socket debugging

[rlibby]

Summary

Display the mbuf/cluster count for a socketbuf and fix a couple
whitespace issues in the output.

Test Plan

db> show socket 0xfffff80004d2f000    
socket at 0xfffff80004d2f000
  so_count: 1   so_type: 3 (SOCK_RAW)
  so_options: 0x0 ()
  so_linger: 0   so_state: 0x0 ()
  so_pcb: 0xfffff80004da01a8   so_proto: 0xffffffff819d1840
  so_proto at 0xffffffff819d1840
    pr_type: 3   pr_domain: 0xffffffff819d0ed0
    pr_domain at 0xffffffff819d0ed0
      dom_family: 2   dom_name: internet
      dom_init: 0   dom_externalize: 0   dom_dispose: 0
      dom_protosw: 0xffffffff819d0f40   dom_next: 0xffffffff819c6ec8
      dom_rtattach: 0xffffffff80bd0150         dom_ifattach: 0xffffffff80bc5510   dom_ifdetach: 0xffffffff80bc55c0
    pr_protocol: 0
    pr_flags: 3 (PR_ATOMIC, PR_ADDR)
    pr_input: 0xffffffff80bd8d00   pr_output: 0   pr_ctlinput: 0
    pr_ctloutput: 0xffffffff80bd9680   pr_init: 0xffffffff80bd8c60
    pr_fasttimo: 0   pr_slowtimo: 0   pr_drain: 0
  so_qstate: 0x0 ()   so_listen: 0   so_timeo: 0   so_error: 0
  so_sigio: 0   so_oobmark: 0
  so_rcv at 0xfffff80004d2f148
    sb_state: 0x0 ()
    sb_mb: 0   sb_mbtail: 0   sb_lastrecord: 0
    sb_sndptr: 0   sb_sndptroff: 0
    sb_acc: 0   sb_ccc: 0   sb_hiwat: 9216   sb_mbcnt: 0   sb_mbmax: 73728
    sb_mcnt: 0   sb_ccnt: 0   sb_ctl: 0   sb_lowat: 1   sb_timeo: 0
    sb_flags: 0x0 ()
    sb_aiojobq first: 0
  so_snd at 0xfffff80004d2f238
    sb_state: 0x0 ()
    sb_mb: 0   sb_mbtail: 0   sb_lastrecord: 0
    sb_sndptr: 0   sb_sndptroff: 0
    sb_acc: 0   sb_ccc: 0   sb_hiwat: 9216   sb_mbcnt: 0   sb_mbmax: 73728
    sb_mcnt: 0   sb_ccnt: 0   sb_ctl: 0   sb_lowat: 2048   sb_timeo: 0
    sb_flags: 0x0 ()
    sb_aiojobq first: 0
db>

[markj]

Approved.

[rlibby]

Resolve conflicts with D9770 / r319722, and also fix up a minor format
issue resulting from it.