Problem compiling gcc 5.2.0 on VortexDX86 embedded

[Renato Mendes <renato dot mendes dot pes at gmail dot com>]

I tried also with an older version of gcc (4.8.2) and got the same
problem in different source file, this time on genconstants.c. Check
the logs:

make[3]: Entering directory `/home/ftp/pub/gcc-build/gcc'
g++ -c   -g -DIN_GCC   -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -W -Wall -Wwrite-strings -Wcast-qual
-Wmissing-format-attribute -fno-common  -DHAVE_CONFIG_H
-DGENERATOR_FILE -I. -Ibuild -I../../gcc-4.8.2/gcc
-I../../gcc-4.8.2/gcc/build -I../../gcc-4.8.2/gcc/../include
-I../../gcc-4.8.2/gcc/../libcpp/include
-I../../gcc-4.8.2/gcc/../libdecnumber
-I../../gcc-4.8.2/gcc/../libdecnumber/bid -I../libdecnumber
-I../../gcc-4.8.2/gcc/../libbacktrace    \
-o build/genconstants.o ../../gcc-4.8.2/gcc/genconstants.c
In file included from ../../gcc-4.8.2/gcc/genconstants.c:28:
../../gcc-4.8.2/gcc/system.h:205:20: cstring: No such file or directory
../../gcc-4.8.2/gcc/genconstants.c: In function `int print_md_constant(void**,
   void*)':
../../gcc-4.8.2/gcc/genconstants.c:38: warning: unused parameter `void*info'
../../gcc-4.8.2/gcc/genconstants.c: In function `int print_enum_type(void**,
   void*)':
../../gcc-4.8.2/gcc/genconstants.c:51: warning: unused parameter `void*info'
make[3]: *** [build/genconstants.o] Error 1
make[3]: Leaving directory `/home/ftp/pub/gcc-build/gcc'
make[2]: *** [all-stage1-gcc] Error 2
make[2]: Leaving directory `/home/ftp/pub/gcc-build'
make[1]: *** [stage1-bubble] Error 2
make[1]: Leaving directory `/home/ftp/pub/gcc-build'
make: *** [all] Error 2