Telling csh about multiple, machine-dependent libraries

[Guy Harris]

>I wonder what "class" and "ident" do?  The cpp(1) page doesn't mention
>them.

"class" is left over from an ancestor of C++, I believe; that language
was named "C with classes" or something like that. 

"ident" is an S5R3-ism; it takes a character string as an argument, and
gets passed through to the compiler, which tells the assembler to stick
the string into a special "SCCS IDs" section of the object file.  That
way, SCCS IDs are in the object file (and in the source file, by virtue
of the "#ident" line), but not in the address space of a process that
runs an executable.  There's a command that will remove the "SCCS IDs"
section, in case you don't want to spend disk blocks on it.

Some systems implement it but don't pass it through to the compiler;
this is done for S5R3 compatibility, so that you don't have to rip the
"#ident" lines out.  4.3BSD and SunOS 4.0 do this.