Remove autotools-related files from .gitignore.

Identify automatically-generated build system components as binary
files through the use of .gitattributes.
Generate build system so the user is not required to run autoreconf.

This is a convenience for certain platforms that may have faulty
autotools environments (OSX, for example), which leads to either
the autoreconf step failing, or to it generating faulty build
systems that can't detect libraries correctly.
Regenerate build system after header fix