Where is -lgcrt1.o?

After upgrading to OSX 10.3, I now find that all my compiles die during
the link stage with the error message:

ld: can't locate file for: -lgcrt1.o

The string "crt1" doesn't occur anywher in any of my files, or in my environment,
or anywhere else I can find.  There are no files with "crt1" in their names on
the disk.  The man command doesn't know about it.  Google doesn't know about it.
A search at apple.com comes up empty.

Anyone know why this is happening?  It's a total showstopper.