blas/native/Dgemm: Remove re-declarations for 1.5
Created by: btracey
Dgemm redeclares a number of variables in the parallel loop to avoid global references. There is a PR to change gc to capture these variables by value, which will render this optimization unnecessary.
https://groups.google.com/forum/#!topic/golang-codereviews/ckUrDjXR5pI