Mostly similar library generation

[Harlan Stenn]

First, I think the ctags/etags example in the docs are wrong, at least
in the more complex example that describes de-ANSI-fication.  In both
the examples the input should be coming from a ._c file and the
resulting file should be a ._o file.  Perhaps better, a combined example
that uses $U?  And the example does not handle non-srcdir builds properly.

Next, I'm currently building libfoo.a, which has a decent number of
source modules.

I now have to build two libraries, libfoo.a and libfoosim.a, where the
only difference between the two libraries is that bar.c is compiled
"normally" for libfoo.a, but for libfoosim.a I need to also supply
-DSIM when compiling bar.c .

As you might imagine, I'm doing this in an environment that must support
de-ANSI-fication.

Ideas?

Harlan