Added a new class to Process.h: ProcessAttachInfo. This class contains enough
info for us to attach by pid, or by name and will also allow us to eventually
do a lot more powerful attaches. If you look at the options for the "platform
process list" command, there are many options which we should be able to
specify. This will allow us to do things like "attach to a process named 'tcsh'
that has a parent process ID of 123", or "attach to a process named 'x' which
has an effective user ID of 345". 

I finished up the --shell implementation so that it can be used without the
--tty option in "process launch". The "--shell" option now can take an 
optional argument which is the path to the shell to use (or a partial name
like "sh" which we will find using the current PATH environment variable).

Modified the Process::Attach to use the new ProcessAttachInfo as the sole
argument and centralized a lot of code that was in the "process attach"
Execute function so that everyone can take advantage of the powerful new
attach functionality.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@144615 91177308-0d34-0410-b5e6-96231b3b80d8
20 files changed