linux-user: do_shmdt(): Fix page_set_flags's 2nd arg.

2nd arg of page_set_flags() should be start+size, but size.

Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>
Acked-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a03e432..26c0fb4 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2752,7 +2752,7 @@
     for (i = 0; i < N_SHM_REGIONS; ++i) {
         if (shm_regions[i].start == shmaddr) {
             shm_regions[i].start = 0;
-            page_set_flags(shmaddr, shm_regions[i].size, 0);
+            page_set_flags(shmaddr, shmaddr + shm_regions[i].size, 0);
             break;
         }
     }