Elevate ProcessInfo and ProcessLaunchInfo into their own headers.
llgs will be using ProcessLaunchInfo but doesn't need to pull in
the rest of Process.h.
This also moves a bunch of implementation details from the header
declarations into ProcessInfo.cpp and ProcessLaunchInfo.cpp.
Tested on Ubuntu 14.04 Cmake and MacOSX Xcode.
Related to https://github.com/tfiala/lldb/issues/26.
llvm-svn: 212005