shill: update Makefile to enable -Wall, and related flags, on ebuilds

Previously, ebuild flags would be used in preference to those in
the Makefile. Now, we append -Wall, and related flags, to those
set by emake.

Also: update existing code to eliminate warnings.

BUG=chromium-os:15877
TEST=emerge

Change-Id: I95f80860edb29e197aef0e08493f78276da3c062
Reviewed-on: http://gerrit.chromium.org/gerrit/1742
Reviewed-by: Chris Masone <cmasone@chromium.org>
Tested-by: mukesh agrawal <quiche@chromium.org>
diff --git a/rtnl_handler.cc b/rtnl_handler.cc
index bcfd020..51c2b88 100644
--- a/rtnl_handler.cc
+++ b/rtnl_handler.cc
@@ -34,10 +34,10 @@
 RTNLHandler::RTNLHandler()
     : running_(false),
       in_request_(false),
-      rtnl_callback_(NewCallback(this, &RTNLHandler::ParseRTNL)),
       rtnl_socket_(-1),
       request_flags_(0),
-      request_sequence_(0) {
+      request_sequence_(0),
+      rtnl_callback_(NewCallback(this, &RTNLHandler::ParseRTNL)) {
   VLOG(2) << "RTNLHandler created";
 }
 
@@ -213,7 +213,7 @@
     struct nlmsghdr *hdr = reinterpret_cast<struct nlmsghdr *>(buf);
     struct nlmsgerr *err;
 
-    if (!NLMSG_OK(hdr, end - buf))
+    if (!NLMSG_OK(hdr, static_cast<unsigned int>(end - buf)))
       break;
 
     switch (hdr->nlmsg_type) {