exit1() to block until any current PHOLD's are released.  This includes
Simplifying the cleanup code in kern_ptrace() and removing the now
unnecessary vmspace ref counting magic from proc_rwmem().  Also, the
locking for ptrace_single_step(), ptrace_set_pc(), and
ptrace_clear_single_step() have been fixed to be consistent across the
tree.

Approved by:	re (scottl)

	kern_sig.c	revision 1.319
	sys_process.c	revision 1.134

	Avoid kernel panic when attaching a process which
	may not be stopped by debugger, e.g process is dumping core.

     kern/kern_kse.c    revision 1.215

     > Fix a LOR between sched_lock and sleep queue lock.

Approved by: re(scottl)

This is good enough to be able to run a RELENG_4 gdb binary against
a RELENG_4 application, along with various other tools (eg: 4.x gcore).
We use this at work.

ia32_reg.[ch]: handle the 32 bit register file format, used by ptrace,
	procfs and core dumps.
procfs_*regs.c: vary the format of proc/XXX/*regs depending on the client
	and target application.
procfs_map.c: Don't print a 64 bit value to 32 bit consumers, or their
	sscanf fails.  They expect an unsigned long.
imgact_elf.c: produce a valid 32 bit coredump for 32 bit apps.
sys_process.c: handle 32 bit consumers debugging 32 bit targets.  Note
	that 64 bit consumers can still debug 32 bit targets.

IA64 has got stubs for ia32_reg.c.

Known limitations: a 5.x/6.x gdb uses get/setcontext(), which isn't
implemented in the 32/64 wrapper yet.  We also make a tiny patch to
gdb pacify it over conflicting formats of ld-elf.so.1.

Approved by:	re

Found by:	Coverity Prevent analysis tool

including other headers.

indicate that a thread is in UTS critical region.

Reviewed by: deischen
Approved by: marcel

 - Push down Giant into shmexit().  (Giant is acquired only if the vmspace
   contains shm segments.)
 - Eliminate the acquisition of Giant from proc_rwmem().
 - Reduce the scope of Giant in exit1(), uncovering the destruction of the
   address space.