disable stucture padded warnings on win64 builds.

BUG=432
TESTED=local win64 build
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/48289004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1389 16f28f9a-4ce2-e073-06de-1de4eb20be90

source/mjpeg_decoder.cc

@@ -18,6 +18,12 @@
 // Must be included before jpeglib.
 #include <setjmp.h>
 #define HAVE_SETJMP
+
+#if defined(_MSC_VER)
+// disable warning 4324: structure was padded due to __declspec(align())
+#pragma warning(disable:4324)
+#endif
+
 #endif
 struct FILE;  // For jpeglib.h.