[PATCH] desc-cpu.scm: support passing the instruction endianness to cgen_cpu_open

[Jose E. Marchesi]

    > The accompanying patch for opcodes will be sent to
    > binutils@sourceware.org today.  This CGEN patch will have to be applied
    > first though.
    > 
    > OK for master?
    
    Sure, and it seems to have been anticipated.
    
Thanks.  I will push once the binutils stuff is also ready... found a
complication.

(Actually, the whole handling of endianness in both CGEN and binutils is
 a mess.  Trying to get some sense of it.)