Suppress gcc 4.x -Wpointer-sign (included in -Wall) warnings

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5275 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a3b975d..0260756 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -947,7 +947,8 @@
                               abi_ulong optval_addr, abi_ulong optlen)
 {
     abi_long ret;
-    int len, lv, val;
+    int len, val;
+    socklen_t lv;
 
     switch(level) {
     case TARGET_SOL_SOCKET: