GCC 4.8.0 does not compile for DJGPP

[Fabrizio Gennari <fabrizio dot ge at tiscali dot it>]

I am trying to build a cross-compiler for DJGPP running on my Ubuntu 
12.10 box.

#../gcc-4.8.0/configure --prefix=<my prefix> --target=i586-pc-msdosdjgpp
#make

[...]

g++ -c -g -O2 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE -fno-exceptions 
-fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing 
-Wwrite-strings -Wcast-qual -Wmissing-format-attribute -pedantic 
-Wno-long-long -Wno-variadic-macros -Wno-overlength-strings 
-DHAVE_CONFIG_H -I. -I. -I../../gcc-4.8.0/gcc -I../../gcc-4.8.0/gcc/. 
-I../../gcc-4.8.0/gcc/../include -I../../gcc-4.8.0/gcc/../libcpp/include 
-I../../gcc-4.8.0/gcc/../libdecnumber 
-I../../gcc-4.8.0/gcc/../libdecnumber/dpd -I../libdecnumber 
-I../../gcc-4.8.0/gcc/../libbacktrace \
../../gcc-4.8.0/gcc/config/i386/i386.c -o i386.o
../../gcc-4.8.0/gcc/config/i386/i386.c: In function âvoid ix86_code_end()â:
../../gcc-4.8.0/gcc/config/i386/i386.c:8650:55: error: 
âASM_DECLARE_FUNCTION_NAMEâ was not declared in this scope

When doing the same with older versions of GCC, it was just a warning

warning: implicit declaration of function âASM_DECLARE_FUNCTION_NAMEâ 
[-Wimplicit-function-declaration]

Note that older versions of GCC used gcc instead of g++

Is there something wrong in GCC, or in what I am doing?

Regards,
Fabrizio