We were using a quad-layout depth format as the destination format for
glReadPixels calls with GL_DEPTH_COMPONENT / GL_FLOAT format. Upload to
a texture was also affected.

Bug b/64542192

Change-Id: I8ad700bf86737debe3268ec6a3dbd237cd85ea1a
Reviewed-on: https://swiftshader-review.googlesource.com/15548Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>