Removing patchlevel.h

Removing patchlevel.h

The significance of this headerfile has now been reduced as pppd now provides
pppd.pc (pkgconfig) and autotools to configure the project. Other projects can
now also configure the correct path variable:

   e.g. /usr/lib/x86_64-linux-gnu/pppd/2.4.10/...

To both consider the architecture and version via pkg-tool. The only consideration
would be the missing DATE directive. But I am less worried about that as the entire
release process has now been changed with the introduction of autotools.

Also fixing up pppd/pppdconf.h.in to remove quotes around the defines

Signed-off-by: Eivind Næss <eivnaes@yahoo.com>