Emacs from BZR (but also 24.1) fails on Gentoo FreeBSD 9.0 during
configure:

   configure: error: Required file(s) not found: crtn.o crt1.o crti.o
   Try using the --with-crt-dir option.
   $ uname -a
   FreeBSD eunomia 9.0-Gentoo FreeBSD Gentoo 9.0 #0: Tue Jul 24 02:42:55 CEST 2012     root@:/usr/src/sys/amd64/compile/GENERIC  amd64

The problem is that crt{1,i,n}.o (which are installed by freebsd-lib)
are located in /usr/lib, whereas crt{begin,end}.o (installed by gcc)
are in /usr/lib/gcc/x86_64-gentoo-freebsd9.0/4.5.3.

Obviously, specifying a location with --with-crt-dir wouldn't help in
this situation, because configure assumes that all crt*.o files are
in the same directory.

Attached patch fixes the problem for me.

(Another question is why crtbegin.o and crtend.o are needed for
linking on FreeBSD, in the first place? Emacs builds and runs here
without apparent problems, even if linked without these files.)