Don't build the 'wells_example' unless UMFPACK is available.

While here, clean up the link-time dependency information.  This
information is inferred from the libopmcore.la Libtool library.

examples/Makefile.am

@@ -2,26 +2,16 @@ AM_CPPFLAGS =					\
 -I$(top_srcdir)					\
 $(BOOST_CPPFLAGS)
 
-LDFLAGS = $(BOOST_LDFLAGS)
-
 LDADD =	$(top_builddir)/libopmcore.la
 
 noinst_PROGRAMS =				\
 scaneclipsedeck
 
 if UMFPACK
-noinst_PROGRAMS += spu_2p
-spu_2p_SOURCES   = spu_2p.cpp
-spu_2p_LDADD     =				\
-$(BOOST_FILESYSTEM_LIB)				\
-$(BOOST_SYSTEM_LIB)				\
-$(LDADD)					\
-$(LAPACK_LIBS)
-endif
+noinst_PROGRAMS +=				\
+spu_2p						\
+wells_example
 
-noinst_PROGRAMS += wells_example
-wells_example_SOURCES   = wells_example.cpp
-wells_example_LDADD     =				\
-$(BOOST_FILESYSTEM_LIB)				\
-$(BOOST_SYSTEM_LIB)				\
-$(LDADD)					
+spu_2p_SOURCES        = spu_2p.cpp
+wells_example_SOURCES = wells_example.cpp
+endif