STY: PEP8 fixups for numpy/random.
BUG: Fix None comparison giving FutureWarning in choice function.

This is in numpy/random/mtrand/mtrand.pyx where the choice function
was using comparisons of the form `None != p`.
Merge pull request #4937 from charris/pep8-numpy-random

Pep8 numpy random
BLD: add debug information to gfortran builds

Similar to C builds which always have debug info.
Merge pull request #4988 from juliantaylor/gfortran-debug

BLD: add debug information to gfortran builds
BUG: don't overwrite input percentile arrays
Merge pull request #4989 from juliantaylor/percentile-fix

BUG: don't overwrite input percentile arrays