Missing lib with Suitesparse 4.4.5

[Marco Atzeri]

Building latest dev source with Cygwin 64, I was forced to

make LIBS="-lsuitesparseconfig"

to complete the build.

It seems that the test for additional library for UMFPACK
is not effective as the problem is also here:

liboctave/array/.libs/libarray.a(liboctave_array_libarray_la-CSparse.o):CSparse.cc:(.rdata$.refptr.
SuiteSparse_hypot[.refptr.SuiteSparse_hypot]+0x0): undefined reference 
to `SuiteSparse_hypot'
liboctave/array/.libs/libarray.a(liboctave_array_libarray_la-CSparse.o):CSparse.cc:(.rdata$.refptr.
SuiteSparse_divcomplex[.refptr.SuiteSparse_divcomplex]+0x0): undefined 
reference to `SuiteSparse_di
vcomplex'
liboctave/array/.libs/libarray.a(liboctave_array_libarray_la-CSparse.o):CSparse.cc:(.rdata$.refptr.
SuiteSparse_config[.refptr.SuiteSparse_config]+0x0): undefined reference 
to `SuiteSparse_config'
collect2: error: ld returned 1 exit status
Makefile:13064: recipe for target 'liboctave/liboctave.la' failed

As almost all the SuiteSparse libraries are now linked to
suitesparseconfig, should be better to check for its existence ?

Regards
Marco