Maintainer mode

[Doug Evans]

Ben Elliston writes:
 > After thinking about it a bit, I am ready to propose that the opcodes
 > and sim Makefile.am's be modified so that they no longer rely on
 > `--enable-cgen-maint', but instead use the @MAINTAINER_MODE@
 > substitutions provided by AM_MAINTAINER_MODE to determine whether or
 > not to include rules for automatically regenerating files.
 > 
 > The advantages here are obvious: you need not remember an extra option
 > to `configure' and it works more obviously.

I recognize the reasons why one would want to do this.
I didn't do this because it carries extra burdens I wasn't prepared
to dump on binutils/gdb people.