suite-sparse 4.1.0: fix CHOLMOD by adding -DNCAMD, use metis4 dep

As of SuiteSparse 4.1.0, the -DNPARTITION option was broken out in to -DNPARTITION
and -DNCAMD. The -DNPARTITION is still used automatically when METIS is not used.
However, it looks like there's a bug in the Makefile causing the libcholmod.a build
to fail when METIS is absent, but it's ignored, so the build succeeds but is missing
libcholmod.a. Added -DNCAMD to fix this and get the old 4.0.2 behavior back.

Also changed the metis dependency to be against formula metis4 (Metis 4.x), since
SuiteSparse is not compatible with METIS 5.x, and homebrew's main metis is 5.x.
suite-sparse: Trivial merge of branch 'master' of https://github.com/Homebrew/homebrew-science

Conflicts:
	suite-sparse.rb

It was just a difference in whitespace.