Signed-off-by: Edward Z. Yang <[email protected]>

Described in: ghc-proposals/ghc-proposals#4

./Setup configure now takes an argument to specify a specific
component name that should solely be configured.

Most of the gyrations in Configure are all about making it so that
we can feed in internal dependencies via --dependency.  I dropped
the package name match sanity check to handle convenience library
package name munging.  I also had to make register/copy unconditionally
install internal libraries; otherwise you can't refer to them
from later builds.

Also a miscellaneous refactor: convenience libraries are printed with a
"header" stanza now (not really a stanza header).

Signed-off-by: Edward Z. Yang <[email protected]>