close_client_ssl_connection(): Set SSL_RECEIVED_SHUTDOWN

close_client_ssl_connection(): Set SSL_RECEIVED_SHUTDOWN

... so the BIO_free_all() call later on does not result
in OpenSSL waiting for a shutdown alert.

Prevents temporary hangs like this:

   (gdb) where
   #0  0x0000000801d1f8da in _read () from /lib/libc.so.7
   #1  0x00000008019aebe6 in __thr_read (fd=26, buf=0x804a2e8c3, nbytes=5) at /usr/src/lib/libthr/thread/thr_syscalls.c:418
   #2  0x0000000800cafb62 in sock_read (b=0x80895ffb0, out=0x804a2e8c3 "\027\003\003\004\a", outl=5) at /usr/src/crypto/openssl/crypto/bio/bss_sock.c:140
   #3  0x0000000800db9f34 in BIO_read (b=0x80895ffb0, out=0x804a2e8c3, outl=5) at /usr/src/crypto/openssl/crypto/bio/bio_lib.c:210
   #4  0x000000080176a80d in ssl3_read_n (s=0x806371a80, n=5, max=5, extend=<optimized out>) at /usr/src/crypto/openssl/ssl/s3_pkt.c:258
   #5  0x000000080176b87c in ssl3_get_record (s=0x806371a80) at /usr/src/crypto/openssl/ssl/s3_pkt.c:342
   #6  ssl3_read_bytes (s=<optimized out>, type=<optimized out>, buf=<optimized out>, len=<optimized out>, peek=0) at /usr/src/crypto/openssl/ssl/s3_pkt.c:1233
   #7  0x000000080176e7bb in ssl3_shutdown (s=0x806371a80) at /usr/src/crypto/openssl/ssl/s3_lib.c:4396
   #8  0x00000008017505b0 in ssl_free (a=0x80895fed0) at /usr/src/crypto/openssl/ssl/bio_ssl.c:126
   #9  0x0000000800dbab7e in BIO_free (a=0x80895fed0) at /usr/src/crypto/openssl/crypto/bio/bio_lib.c:133
   #10 BIO_free_all (bio=0x0) at /usr/src/crypto/openssl/crypto/bio/bio_lib.c:509
   #11 0x000000000045b301 in free_client_ssl_structures (csp=0x807678a88) at openssl.c:907
   #12 0x000000000045b391 in close_client_ssl_connection (csp=0x807678a88) at openssl.c:883
   #13 0x0000000000438603 in serve (csp=0x807678a88) at jcc.c:4516
   #14 0x00000008019ac08c in thread_start (curthread=0x807744200) at /usr/src/lib/libthr/thread/thr_create.c:290
   #15 0x0000000000000000 in ?? ()