(bib) libobjc build failure

[Nathanael Nerode]

On b-i-b (i686-pc-linux-gnu), I'm getting a failure to build libobjc; 
it's complaining that BITS_PER_UNIT is not defined in "encoding.c".

It took me a loooong time to track this down.  It's caused by Zack's 
big patch to get proper dependencies on tm.h.  The old 'tconfig.h' 
contained a bunch of includes conditioned on '#ifdef IN_GCC'.
The new 'tconfig.h' contains *only* "ansidecl.h".

The change is due to this change in configure.in:
-xm_file="ansidecl.h ${xm_file} ${tm_file}"
+xm_file="ansidecl.h ${xm_file}"

It seems that the Makefile.in for libobjc passes -DIN_GCC to all 
compiles.  So encoding.c used to get various things defined in 
${tm_file} files, and now it doesn't.

Zack, can you figure out the correct way to fix this?
Either you need to change something, or libobjc needs to change 
something, and I'm not sure which.

--Nathanael