Bug#1909: autoconf.h missing

[Mark Eichin <eichin@cygnus.com>]

/usr/include/linux/autoconf.h has nothing to do with the autoconf
package, but might have to do with the libc/source packaging
issues. There is a
	/usr/src/linux/include/linux/autoconf.h
which is probably what you want; compiling ftape *probably* needs
to simply use -I/usr/src/linux/include. I've reassigned this to
"source", which may be wrong (it should perhaps be assigned to ftape,
but emphatically not to autoconf, as linux just happens to use that
name for the mechanism it uses too.)