<rdar://problem/13121056>

Fixed a crasher when the ConnectionFileDescriptor was used in a process with over FD_SETSIZE (1024) files open. It would corrupt the stack and cause the stack checker to assert and kill the program.

The final fix was to "#define _DARWIN_UNLIMITED_SELECT" at the top of the one and only file that uses select () in the LLDB codebase and then make an array of "fd_set" objects so they can handle more than 1024 file descriptors. The new code can handle as many file descriptors as a process can create.