Match Octave/Numpy's minimum RWORK size for gesdd. Fixes #4016

gesdd's RWORK size was recently changed to match the netlib header.
However, the minimum size calculated results in a segfault.  Both
Octave and Numpy use a different minimum size, and testing verified
that anything smaller than this leads to a segfault.

Numpy: https://github.com/numpy/numpy/blob/master/numpy/linalg/umath_linalg.c.src#L2922
Octave: http://hg.savannah.gnu.org/hgweb/octave/file/2f1729cae08f/liboctave/numeric/CmplxSVD.cc#l184
Merge branch 'master' of https://github.com/JuliaLang/julia