Add libssl-dev dependency

Adds libcrypto package for phosphor-net-ipmid

Change-Id: Iee95081465e361bbd6e1911f7a18963cd8d7c357
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index 12de65b..69985e7 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -55,6 +55,7 @@
     pkg-config \
     autoconf \
     libsystemd-dev \
+    libssl-dev \
     sudo \
     wget \
     git