Tiny patch to add tensorflow support

[bigntallmike]

If necessary, I can submit a pull request, it just feels excessive for this tiny offering.
Basically, I wanted tensorflow support, so I edited the build script and added it as a configure option as seen below, and it worked. ymmv.

diff --git a/build-ffmpeg b/build-ffmpeg
index 326145f..0c731d0 100755
--- a/build-ffmpeg
+++ b/build-ffmpeg
@@ -231,6 +231,7 @@ while (($# > 0)); do
     if [[ "$1" == "--enable-gpl-and-non-free" ]]; then
       CONFIGURE_OPTIONS+=("--enable-nonfree")
       CONFIGURE_OPTIONS+=("--enable-gpl")
+      CONFIGURE_OPTIONS+=("--enable-libtensorflow")
       NONFREE_AND_GPL=true
     fi