The current file's directory, ".", is treated much more literally
when building libvpx examples with Xcode than it is with make, and
clang cannot find common include files included via "./" when those
files actually reside one directory up in the tree.
Change-Id: I5f66a026282e35d80248ca4052ebb882b859172e
Right now only IVF format is supported which is enough for example code.
Other formats like y4m, webm, raw yuv will be supported later.
Change-Id: I34c6f20731c1851947587ca5c589d7856b675164
