fix /proc/self/maps output

Add a space at end of line when there is no filename to print, to
conform to linux kernel format (see show_map_vma() in
fs/proc/task_mmu.c).
Signed-off-by: NChristophe Lyon <christophe.lyon@linaro.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

linux-user/syscall.c

@@ -5050,10 +5050,10 @@ static int open_self_maps(void *cpu_env, int fd)
         }
         if (h2g_valid(min) && h2g_valid(max)) {
             dprintf(fd, TARGET_ABI_FMT_lx "-" TARGET_ABI_FMT_lx
-                    " %c%c%c%c %08" PRIx64 " %02x:%02x %d%s%s\n",
+                    " %c%c%c%c %08" PRIx64 " %02x:%02x %d %s%s\n",
                     h2g(min), h2g(max), flag_r, flag_w,
                     flag_x, flag_p, offset, dev_maj, dev_min, inode,
-                    path[0] ? "          " : "", path);
+                    path[0] ? "         " : "", path);
         }
     }