xgcc unable to build libgcc under mingw

["Alexander Shabanov" <avshabanov@gmail.com>]

Hello!

As I said in my previous question - I tried to compile gcc under
mingw. If we want to compile gcc under mingw, we must specify path to
`ld', like '../configure --with-ld=/mingw/bin/ld'. Compilers built
fine - we obtain $(MINGW_OBJDIR)/gcc/cc1plus, cc1, xgcc, etc. After
building makefile tried to build libgcc using xgcc, but unable to do
it:

--------------------- BEGIN
make[3]: Entering directory `/d/GnuProjects/gcc/gcc-4.1.1/obj_mgw_nostdcpp/gcc'

/d/GnuProjects/gcc/gcc-4.1.1/obj_mgw_nostdcpp/./gcc/xgcc
-B/d/GnuProjects/gcc/gcc-4.1.1/obj_mgw_nostdcpp/./gcc/
-B/usr/local/i686-pc-mingw32/bin/ -B/usr/local/i686-pc-mingw32/lib/
-isystem /usr/local/i686-pc-mingw32/include -isystem
/usr/local/i686-pc-mingw32/sys-include -O2
-I../../gcc/../winsup/w32api/include -O2 -g -O2   -DIN_GCC    -W -Wall
-Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes
-Wold-style-definition  -isystem ./include   -g -DHAVE_GTHR_DEFAULT
-DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED  -I. -I. -I../../gcc
-I../../gcc/. -I../../gcc/../include -I./../intl
-I../../gcc/../libcpp/include  -DL_negdi2 -c ../../gcc/libgcc2.c -o
libgcc/./_negdi2.o
In file included from ../../gcc/libgcc2.c:33:
../../gcc/tsystem.h:90:19: error: stdio.h: No such file or directory
../../gcc/tsystem.h:93:23: error: sys/types.h: No such file or directory
../../gcc/tsystem.h:96:19: error: errno.h: No such file or directory
../../gcc/tsystem.h:103:20: error: string.h: No such file or directory
../../gcc/tsystem.h:104:20: error: stdlib.h: No such file or directory
../../gcc/tsystem.h:105:20: error: unistd.h: No such file or directory
In file included from ./include/limits.h:122,
--------------------- END
As I understood, it happens, because makefile script unable to find
correct path to sysincludes headers.

Please, explain, how can I fix it?

-- 
Best regards,
    Alexander Shabanov