[mingw, libiberty]build warnings with latest binutils-gdb git head

[asmwarrior]

I just build GDB under WinXP, with MSYS+MinGW GCC4.8.2 compiler, I get some warnings when building libiberty target.

Here is the related log:
----------------------------------------------------

if [ x"" != x ]; then \
	  gcc -c -DHAVE_CONFIG_H -O0 -g -D__USE_MINGW_ACCESS  -I. -I../../binutils-gdb/libiberty/../include  -W -Wall -Wwrite-strings -Wc++-compat -Wstrict-prototypes -pedantic   ../../binutils-gdb/libiberty/strerror.c -o pic/strerror.o; \
	else true; fi
gcc -c -DHAVE_CONFIG_H -O0 -g -D__USE_MINGW_ACCESS  -I. -I../../binutils-gdb/libiberty/../include  -W -Wall -Wwrite-strings -Wc++-compat -Wstrict-prototypes -pedantic  ../../binutils-gdb/libiberty/strerror.c -o strerror.o
In file included from ../../binutils-gdb/libiberty/strerror.c:31:0:
../../binutils-gdb/libiberty/strerror.c:472:12: warning: '_sys_nerr' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
 extern int sys_nerr;
            ^
../../binutils-gdb/libiberty/strerror.c:473:14: warning: '_sys_errlist' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
 extern char *sys_errlist[];
              ^
----------------------------------------------------
if [ x"" != x ]; then \
	  gcc -c -DHAVE_CONFIG_H -O0 -g -D__USE_MINGW_ACCESS  -I. -I../../binutils-gdb/libiberty/../include  -W -Wall -Wwrite-strings -Wc++-compat -Wstrict-prototypes -pedantic   ../../binutils-gdb/libiberty/waitpid.c -o pic/waitpid.o; \
	else true; fi
gcc -c -DHAVE_CONFIG_H -O0 -g -D__USE_MINGW_ACCESS  -I. -I../../binutils-gdb/libiberty/../include  -W -Wall -Wwrite-strings -Wc++-compat -Wstrict-prototypes -pedantic  ../../binutils-gdb/libiberty/waitpid.c -o waitpid.o
../../binutils-gdb/libiberty/waitpid.c: In function 'waitpid':
../../binutils-gdb/libiberty/waitpid.c:31:7: warning: implicit declaration of function 'wait' [-Wimplicit-function-declaration]
       int wpid = wait(stat_loc);
       ^
----------------------------------------------------

Hope they will be fixed, thanks.

Yuanhui Zhang