Added a NACL_ASSERT_SAME_SIZE macro, for checking (at compile time) that two types are the same size.
Added a NACL_ASSERT_SAME_SIZE macro, for checking (at compile time) that two
types are the same size.

The initial use for this is casting data pointers to function pointers during platform qualification.  Since ISO C doesn't specify that the two types of pointers are the same size, but in practice it holds on all our current platforms (since the AS/400 port is still young).  This assert can help guard against any future silliness in this area.
Review URL: http://codereview.chromium.org/1518022

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@2032 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client