Fix a MinGW warning in libiberty/strerror.c

[Kai Tietz]

Hi Eli,

patch is reasonable and ok for me.

Thanks
Kai

2015-01-16 12:18 GMT+01:00 Eli Zaretskii <eliz@gnu.org>:
> Ping!
>
>> Date: Fri, 02 Jan 2015 12:54:47 +0200
>> From: Eli Zaretskii <eliz@gnu.org>
>>
>> When compiling GDB 7.8.1, I get this warning in libiberty:
>>
>>      gcc -c -DHAVE_CONFIG_H -O0 -g3 -D__USE_MINGW_ACCESS  -I. -I./../include  -W -Wall -Wwrite-strings -Wc++-compat -Wstrict-prototypes -pedantic  ./strerror.c -o strerror.o
>>      ./strerror.c:472:12: warning: '_sys_nerr' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
>>      ./strerror.c:473:14: warning: '_sys_errlist' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
>>
>> This happens because the MinGW system headers have some special magic
>> for these variables, which are imported from a system shared library.
>>
>> The solution I propose is to refrain from declaring variables that are
>> actually macros, because this should be a sign that something tricky
>> is going on:
>>
>> --- libiberty/strerror.c~0    2014-06-11 18:34:41 +0300
>> +++ libiberty/strerror.c      2014-12-30 08:12:00 +0200
>> @@ -469,8 +469,13 @@
>>
>>  #else
>>
>> +
>> +#ifndef sys_nerr
>>  extern int sys_nerr;
>> +#endif
>> +#ifndef sys_errlist
>>  extern char *sys_errlist[];
>> +#endif
>>
>>  #endif
>>
>>
>> OK to commit this (with a suitable ChangeLog entry)?
>>