TST: Mark test_big_arrays as knownfail on Mac.

The test was supposed to test a fix for reading big zip files on Mac,
but creating the big test files fails.
Merge pull request #3875 from charris/mark-knownfail-test_big_arrays

TST: Mark test_big_arrays as knownfail on Mac.
TST: linalg: add more comprehensive test cases for linalg funcs

Also remove TestCase subclassing, so that generator tests work.  Also
fix bugs in the existing generator tests that were not actually run
previously.
BUG: linalg: use correct BLAS incx convention in xCOPY
BUG: linalg: fix eigvalsh return type (always real-valued)
MAINT: linalg: strip out unused gufuncs_linalg code

Some of the functions removed were untested, and apparently did not
function correctly (cholesky_up, inner1d, maybe more).
TST: linalg: add slightly bigger test case + don't catch KeyboardInterrupt
TST: linalg: better rtol choice
Merge pull request #3881 from charris/backport-1.8-3880

Backport 1.8 3880
DOC: Update 1.8.0 release notes.

Order highlights by significance. This is a subjective judgement.
Mention the linalg enhancements and illustrate with an example.
Merge pull request #3891 from charris/backport-1.8-3886

Backport 1.8 3886
BUG: Disable check for oldstyle classes in python3

Fixes gh-2561
TST: Regression test for gh-2561
TST: Raise AssertionError on failure
Merge pull request #3898 from juliantaylor/py3-info-1.8

backport PR #3885 to 1.8.x
BUG: linalg: don't tell BLAS to use zero strides

At least OSX Accelerate fails for this case.
STY: linalg: fix C comment style
Merge pull request #3903 from charris/backport-1.8-3902

Backport 1.8 3902