ENH: Import the ccosh/ccos implementation from FreeBSD

The code from FreeBSD was lightly adapted to fit with the numpy style
and to correct an Annex G failure. (ccosh(Inf + 0j) should be (Inf + 0),
and symmetric).

With this commit, npy_ccosh(f) and npy_ccos(f) pass all of the tests in
test_c99complex.c.