snarfer guard macro name decision: SCM_MAGIC_SNARFER

[Thien-Thi Nguyen]

this was used in 1.4.

libguile-1.6 .c source uses it as #ifndef, however both snarf.h and
guile-snarf have been in the meantime changed to not define this.

1.6 snarfing differs from 1.4 primarily in that there are now two kinds:
init and doc, as opposed to merely init.  in defining the names of the
specialization-trigger macros, we now remember usage of this old friend
(i.e., also as guard).

in the end, it is better to migrate self-guard naming internally, and
include that info in the data stream only (snarfing programs generate
program fragments opaque to all re-snarfing).

so, this is sort of a good-bye from public view for SCM_MAGIC_SNARFER
the cpp macro.  [band plays.]

anyone know what are the official namespaces allowed for programs that
munge the cpp macro space?  [macro looks up, wisened and ready for the
inevitable coup.  it is prepared to don a blade, but it has been heard
that the really crafty old dictators (the ones who stayed alive) mingled
and mewed and were the only ones allowed to slit their own throats.]

thi