This patch greatly extends the OS information types available to the user using 
the 'info os' command in Linux. Since the OS info backend is now unified, this 
information can be obtained from both local and remote (gdbserver) targets.

The new information types are:

procgroups - Process groups
files - File descriptors
sockets - Internet-domain sockets
shm - Shared memory regions
semaphores - Semaphores
msg - Message queues
modules - Loaded kernel modules

They all work in the same manner as the existing 'processes' and 'threads' 
information types - by pulling the information from the /proc filesystem and 
formatting it into a table.

This facility is tested using a program which creates file descriptors, sockets 
and IPC structures with specific port numbers/targets, and the test script then 
looks for these in the output of 'info os'.

The documentation is also updated regarding these information types.

Kwok Cheung Yeung


ChangeLog:

gdb/
	* common/linux-osdata.c (compare_processes): Auxiliary function for
	linux_xfer_osdata_processgroups.
	(linux_xfer_osdata_processgroups): New function to
	look up process groups.
	(linux_xfer_osdata_fds): New function to look up file descriptors.
	(format_socket_state, print_sockets): Auxiliary functions for
	linux_xfer_osdata_isockets.
	(union socket_addr): New union used to avoid strict-aliasing problems.
	(linux_xfer_osdata_isockets): New function to look up internet sockets.
	(time_from_int, group_from_gid): New convenience functions for
	converting between data types.	
	(linux_xfer_osdata_shm): New function to look up shared memory for IPC.
	(linux_xfer_osdata_sem): New function to look up semaphores for IPC.
	(linux_xfer_osdata_msg): New function to look up message queues for
	IPC.
	(linux_xfer_osdata_modules): New function to look up loaded kernel
	modules.
	(osdata_table): Add new entries.

gdb/doc/
	* gdb.texinfo (Operating System Auxilliary Information): Document new
	'info os' commands.

gdb/testsuite/
	* gdb.base/info-os.exp: New test to exercise the 'info os *' commands.
	* gdb.base/info-os.c: New test program used by info-os.exp.