src/lt1: include, build and test ltsha1 utility

src/lt1: include, build and test ltsha1 utility

Prepare for future use of the LibTomCrypt SHA-1 implementation by
including it along with a test program and script in a similar
fashion to the way the LibTomCrypt SHA-256 implementation has been
included.

Although the standalone ltsha1 utility is not expected to be used
directly (and is not installed by install.sh), it provides a means
to test the implementation to verify that it's working correctly
which install.sh does.

Add the test script to the scripts run by "make test" in the src
subdirectory.

The LibTomCrypt code <https://www.libtom.net/LibTomCrypt/> has a
very liberal license that is fully compatible with GPLv2.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>