Based on my_error.cc from newer MySQL

--- a/mysys/my_error.c
+++ b/mysys/my_error.c
@@ -110,7 +110,7 @@
        (defined _XOPEN_SOURCE   && (_XOPEN_SOURCE >= 600)))      &&    \
       ! defined _GNU_SOURCE
     strerror_r(nr, buf, len);             /* I can build with or without GNU */
-#elif defined _GNU_SOURCE
+#elif defined(__GLIBC__) && defined(_GNU_SOURCE)
     char *r= strerror_r(nr, buf, len);
     if (r != buf)                         /* Want to help, GNU? */
       strmake(buf, r, len - 1);           /* Then don't. */