[Yhc] build system issues

[Malcolm Wallace]

Here are some observations about yhc's build system.

(1) "scons install" doesn't seem to install anything.  How do I install
    yhc to a standard location after building it?

(2) If there is a problem with any of the scons configuration steps
    (e.g. libgmp or wrong version of ghc found), then "scons help" does
    not work at all.  I thus had several days of chasing configuration
    issues before I could even get scons to give me its usage message!

(3) There seems to be no way to tell scons to use a particular version
    of ghc to bootstrap with, if I happen to have several installed and
    want to use a specific one.  (This is especially a problem if my
    default version is too old for yhc, like ghc-6.2.2, but for other
    software I don't want to change the default.)

(4) There seems to be no way to tell scons to use specific build options
    e.g. on my powerpc G5, it would be useful to give -mcpu=g5 to all C
    compilations, so that it will link properly against the 64-bit libgmp
    that is installed.  I can imagine wanting to give a bunch of options
    to the haskell compiler we are bootstrapping with too.

Would these be difficult to fix?

Regards,
    Malcolm