Hi,

I've committed the attached patch. It causes cgen to look for included 
files in the same directory as specified by the -a option (i.e. same as 
the original input file). The previous behaviour was to look in 
$srcdir/cgen/cpu which is obviously not correct when processing files 
from $srcdir/cpu. If -a is not specified, then all files are obtained 
form $srcdir/cgen/cpu (unchanged from before).

Let me know if there are any problems or concerns.

Dave