Fix compilation of sparc-linux rtl with -dFPC_USE_LIBC

(cherry picked from commit 1433c4f2f8b8c892ffb9bcb7a4bd1821e3ab8124)

rtl/linux/sparc/stat.inc

@@ -108,7 +108,7 @@
       st_ctime,
       st_ctime_nsec,
       __unused4_,
-      __unused5-) : cULong);
+      __unused5_ : cULong);
   end;
 
 {$ENDIF FPC_USE_LIBC}