Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.

llvm-svn: 16137

specific.

llvm-svn: 16119

note individually but these essence of it is to not derive from
std::string, clarify the interface, and provide better documentation.
There is now also (untested) implementations for AIX, Darwin, and SunOS.

llvm-svn: 16078

llvm-svn: 16048