Add autogen.sh from libsigrok4DSLogic

Previously, we had a configure script but no Makefile.in's.

Add this to genereate those files dynamically.

Signed-off-by: Anders Darander <anders@chargestorm.se>
Add instructions to run autogen.sh to libusb

As this will autogenerate the configure script, remove that one from git.

Signed-off-by: Anders Darander <anders@chargestorm.se>
Merge pull request #33 from darander/autotools

Fix issue #32: libusb