Add support for 'info proc files' on FreeBSD core dumps.

Add support for 'info proc files' on FreeBSD core dumps.

Walk the list of struct kinfo_file objects in the
NT_FREEBSD_PROCSTAT_FILES core dump note outputting a description of
each open file descriptor.  For sockets, the local and remote socket
addresses are displayed in place of the file name field.  For UNIX
local domain sockets, only a single address is displayed since most
UNIX sockets only have one valid address and printing both pathnames
could be quite long.  The output format was somewhat inspired by the
output of the "procstat -f" command on FreeBSD, but with a few less
details and some fields were condensed.

gdb/ChangeLog:

	* fbsd-tdep.c (KF_FLAGS, KF_OFFSET, KF_VNODE_TYPE, KF_SOCK_DOMAIN)
	(KF_SOCK_TYPE, KF_SOCK_PROTOCOL, KF_SA_LOCAL, KF_SA_PEER)
	(KINFO_FILE_TYPE_SOCKET, KINFO_FILE_TYPE_PIPE)
	(KINFO_FILE_TYPE_FIFO, KINFO_FILE_TYPE_KQUEUE)
	(KINFO_FILE_TYPE_CRYPTO, KINFO_FILE_TYPE_MQUEUE)
	(KINFO_FILE_TYPE_SHM, KINFO_FILE_TYPE_SEM, KINFO_FILE_TYPE_PTS)
	(KINFO_FILE_TYPE_PROCDESC, KINFO_FILE_FD_TYPE_ROOT)
	(KINFO_FILE_FD_TYPE_JAIL, KINFO_FILE_FD_TYPE_TRACE)
	(KINFO_FILE_FD_TYPE_CTTY, KINFO_FILE_FLAG_READ)
	(KINFO_FILE_FLAG_WRITE, KINFO_FILE_FLAG_APPEND)
	(KINFO_FILE_FLAG_ASYNC, KINFO_FILE_FLAG_FSYNC)
	(KINFO_FILE_FLAG_NONBLOCK, KINFO_FILE_FLAG_DIRECT)
	(KINFO_FILE_FLAG_HASLOCK, KINFO_FILE_FLAG_EXEC)
	(KINFO_FILE_VTYPE_VREG, KINFO_FILE_VTYPE_VDIR)
	(KINFO_FILE_VTYPE_VCHR, KINFO_FILE_VTYPE_VLNK)
	(KINFO_FILE_VTYPE_VSOCK, KINFO_FILE_VTYPE_VFIFO, FBSD_AF_UNIX)
	(FBSD_AF_INET, FBSD_AF_INET6, FBSD_SOCK_STREAM, FBSD_SOCK_DGRAM)
	(FBSD_SOCK_SEQPACKET, FBSD_IPPROTO_ICMP, FBSD_IPPROTO_TCP)
	(FBSD_IPPROTO_UDP, FBSD_IPPROTO_SCTP): New defines.
	(struct fbsd_sockaddr_in, struct fbsd_sockaddr_in6)
	(struct fbsd_sockaddr_un): New types.
	(fbsd_file_fd, fbsd_file_type, fbsd_file_flags, fbsd_ipproto)
	(fbsd_print_sockaddr_in, fbsd_print_sockaddr_in6)
	(fbsd_info_proc_files_header, fbsd_info_proc_files_entry)
	(fbsd_core_info_proc_files): New functions.
	(fbsd_core_info_proc): List open file descriptors for IP_FILES and
	IP_ALL.
	* fbsd-tdep.h (fbsd_info_proc_files_header)
	(fbsd_info_proc_files_entry): New.