Enhance the Pipe interface for better portability.

This patch makes a number of improvements to the Pipe interface.

1) An interface (PipeBase) is provided which exposes pure virtual
   methods for any implementation of Pipe to override.  While not
   strictly necessary, this helps catch errors where the interfaces
   are out of sync.

2) All methods return lldb_private::Error instead of returning bool
   or void.  This allows richer error information to be propagated
   up to LLDB.

3) A new ReadWithTimeout() method is exposed in the base class and
   implemented on Windows.

4) Support for both named and anonymous pipes is exposed through the
   base interface and implemented on Windows.  For creating a new
   pipe, both named and anonymous pipes are supported, and for
   opening an existing pipe, only named pipes are supported.

New methods described in points #3 and #4 are stubbed out on posix,
but fully implemented on Windows.  These should be implemented by
someone on the linux / mac / bsd side.

Reviewed by: Greg Clayton, Oleksiy Vyalov
Differential Revision: http://reviews.llvm.org/D6686

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@224442 91177308-0d34-0410-b5e6-96231b3b80d8
Work around an internal compiler error in MSVC.

For some reason MSVC ICEs when trying to index into a map using
a temporary object.  Work around this by separating out the call
into multiple lines.

Patch by Aidan Dodds
Differential Revision: http://reviews.llvm.org/D6702
Reviewed by: Zachary Turner, Greg Clayton

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@224443 91177308-0d34-0410-b5e6-96231b3b80d8