Uniform block members should not be validated against the
GL_MAX_VERTEX_UNIFORM_VECTORS and GL_MAX_FRAGMENT_UNIFORM_VECTORS
limits. Instead, block sizes should not exceed MAX_UNIFORM_BLOCK_SIZE.

Also move uniform block index validation to the entry functions.

Bug b/111803744

Change-Id: I0ea530813d1f2c29141dc64a93aa10f50460885b
Reviewed-on: https://swiftshader-review.googlesource.com/20028Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>