1. Change the usage of LOADABLE_MODULE so that it implies all the things
   necessary to make a loadable module. This reduces the user's burdern to
   get a loadable module correctly built.
2. Document the usage of LOADABLE_MODULE in the MakefileGuide
3. Adjust the makefile for lib/Transforms/Hello to use the new specification
   for building loadable modules
4. Adjust the sample project to not attempt to build a shared library for
   its little library. This was just wasteful and not instructive at all.

llvm-svn: 29551