Targets can now specify some additional parameters for when we debug 
executables that can help with plug-in selection:

target.execution-level = auto | user | kernel
target.execution-mode  = auto | dynamic | static
target.execution-os-type = auto | none | halted | live

On some systems, the binaries that are created are the same wether you use
them to debug a kernel, or a user space program. Many times inspecting an 
object file can reveal what an executable should be. For these cases we can
now be a little more complete by specifying wether to detect all of these
things automatically (inspect the main executable file and select a plug-in
accordingly), or manually to force the selection of certain plug-ins.

To do this we now allow the specficifation of wether one is debugging a user
space program (target.execution-level = user) or a kernel program 
(target.execution-level = kernel).

We can also specify if we want to debug a program where shared libraries
are dynamically loaded using a DynamicLoader plug-in 
(target.execution-mode = dynamic), or wether we will treat all symbol files
as already linked at the correct address (target.execution-mode = static).

We can also specify if the inferior we are debugging is being debugged on 
a bare board (target.execution-os-type = none), or debugging an OS where
we have a JTAG or other direct connection to the inferior stops the entire
OS (target.execution-os-type = halted), or if we are debugging a program on
something that has live debug services (target.execution-os-type = live).

For the "target.execution-os-type = halted" mode, we will need to create 
ProcessHelper plug-ins that allow us to extract the process/thread and other
OS information by reading/writing memory.

This should allow LLDB to be used for a wide variety of debugging tasks and
handle them all correctly.

llvm-svn: 125815