support rpath for GNU Fortran compiler.

Similar to C builds which always have debug info.

Note that there are a few similar patches posted to gh-4101 and gh-4245.
Those were all patches to msvc9compiler in Python distutils.
Monkeypatching ``MSVCCompiler.link`` is less easy than this change
to ``config._check_compiler``; effect should be the same.

Also updates the error message shown when initializing MSVC fails.

[ci skip]

add openblas_lapack info which checks if it embedds lapack so
lapack_info will point to openblas
the normal openblas info does not check so it may or may not embed
lapack.
closes gh-4192

the get_libs function assumes there is no default to return the default
it was asked to return in that case.
Closes gh-4607

This private variable has disappeared in later versions of setuptools.
In older versions of setuptools it is the same as
distutils.command.install.install, so use that instead.

Closes #4664.

makes attribute checks more sane and allows adding nonnull

The "-Wl,-undefined,dynamic_lookup" flag is enough to make things work
with OS X bundles.  On the mailing list an issue was reported with
Anaconda (non-framework build) where f2py was picking up the system framework
Python instead of the Anaconda one.

Thanks to Robert Kern for explaining how to fix this.