Don't swallow eglCreateContext errors

If the implementation eglCreateContext failed, we called
eglGetError(), so we could check that it set the EGL error properly.
But since we'd already called this, when the app called eglGetError()
it would get EGL_SUCCESS!

Bug: 10181333
Change-Id: Ic45d3a8fcb8c4421e04844c6d2f52761790b5948