Remove some NS_IMPL_GNUSTEP build dead code.

Remove some NS_IMPL_GNUSTEP build dead code.

* configure.in (NS_IMPL_GNUSTEP_INC, NS_IMPL_GNUSTEP_TEMACS_LDFLAGS)
(GNUSTEP_MAKEFILES): Remove.
(LD_SWITCH_SYSTEM_TEMACS): Move NS_IMPL_GNUSTEP_TEMACS_LDFLAGS
stuff to here.

* src/Makefile.in (NS_IMPL_GNUSTEP_INC, NS_IMPL_GNUSTEP_TEMACS_LDFLAGS):
Remove.
(TEMACS_LDFLAGS): Do not use NS_IMPL_GNUSTEP_TEMACS_LDFLAGS.

* msdos/sed1v2.inp (NS_IMPL_GNUSTEP_INC, NS_IMPL_GNUSTEP_TEMACS_LDFLAGS):
No longer present.

Comments:
See http://lists.gnu.org/archive/html/emacs-devel/2010-05/msg00846.html.
Nothing from gui.make was used at all in src/Makefile.in.  The only
thing used from base.make was $CONFIG_SYSTEM_LIBS, but because we only
set shared _after_ sourcing base.make, it was always empty.  We can
move the remaining flags, set in configure, to the standard variable
LD_SWITCH_SYSTEM_TEMACS.