don't install some internal headers and template sources * sparse-chol-inst.cc: Delete. Instantiate needed classes and functions in sparse-chol.cc. * sparse-lu-inst.cc: Delete. Instantiate needed classes and functions in sparse-lu.cc. * sparse-qr-inst.cc: Delete. Instantiate needed classes and functions in sparse-qr.cc. * sighandlers.h: Include sys/types.h. Don't include syswait.h or siglist.h * sparse-chol.h, sparse-qr.h: Don't include oct-sparse.h. * symbfact.cc, sparse-dmsolve.cc: Include oct-sparse.h. * octave.cc: Include siglist.h. * liboctave/numeric/module.mk: Don't install sparse-chol.cc, sparse-lu.cc, or sparse-qr.cc with header files. * liboctave/util/module.mk: Don't install oct-sparse.h. * liboctave/system/module.mk: Don't install pathlen.h, sysdir.h, or syswait.h header files.