LICENSE.txt: add BLAS license.

LICENSE.txt

@@ -63,3 +63,23 @@ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----
+
+apps/linear_algebra/include/cblas.h is licensed under the BLAS license.
+
+The reference BLAS is a freely-available software package. It is available from
+netlib via anonymous ftp and the World Wide Web. Thus, it can be included in
+commercial software packages (and has been). We only ask that proper credit be
+given to the authors.
+
+Like all software, it is copyrighted. It is not trademarked, but we do ask the
+following:
+
+If you modify the source for these routines we ask that you change the name of
+the routine and comment the changes made to the original.
+
+We will gladly answer any questions regarding the software. If a modification is
+done, however, it is the responsibility of the person who modified the routine
+to provide support.
+