Hi!
While conducting a study inspired by the "reproducible builds" practice [1], we have noticed that the package libjpeg-turbo could not be built reproducibly.

After investigation, we observe that the unreproducibility is caused by the "configure" script, in which the output of `date` is captured. 

The attached patch substitutes the `date` according to the SOUR_DATE_EPOCH.  Once applied, libjpeg-turbo could be built deterministically.

 [1]: https://wiki.debian.org/ReproducibleBuilds