Program now uses Attribute location.

Change-Id: I005d64509e4b1e2dd977db38b6b2c41d6ba7ddef
Reviewed-on: https://swiftshader-review.googlesource.com/3722Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>