Travis: Disable unit tests in scan-build config

.travis.sh

@@ -45,7 +45,7 @@ fi
 if [ "$TRAVIS_OS_NAME" = "linux" ]; then
   if [ $ANALYZE = "ON" ] ; then
     if [ "$CC" = "clang" ]; then
-        scan-build cmake -G "Unix Makefiles" -DBUILD_SHARED_LIBS=OFF
+        scan-build cmake -G "Unix Makefiles" -DBUILD_SHARED_LIBS=OFF -DASSIMP_BUILD_TESTS=OFF
         scan-build --status-bugs make -j2
     else
         cppcheck --version