- LIBRARY is now a SUBST variable.

- Add CFLAGSFORSHARED variable.  configure sets this to CCSHARED if LDLIBRARY
  is a shared library.
- Remove -fPIC from OPT, it has no business there.
- Change CCSHARED option for Linux to -fPIC.  It should probably be
  -fPIC on a few other platforms as well.
- Don't create silly boot Makefile, create Setup files and run makesetup
  instead.