travis: Don't run unit tests for functionaltest-lua build

ci/common/build.sh

@@ -71,9 +71,11 @@ build_nvim() {
       exit 1
     fi
 
-    echo "Building nvim-test."
-    if ! top_make nvim-test ; then
-      exit 1
+    if test "${FUNCTIONALTEST}" != "functionaltest-lua"; then
+      echo "Building nvim-test."
+      if ! top_make nvim-test ; then
+        exit 1
+      fi
     fi
   fi
 

ci/run_tests.sh

@@ -22,7 +22,9 @@ enter_suite tests
 if test "$CLANG_SANITIZER" != "TSAN" ; then
   # Additional threads are only created when the builtin UI starts, which
   # doesn't happen in the unit/functional tests
-  run_test run_unittests
+  if test "${FUNCTIONALTEST}" != "functionaltest-lua"; then
+    run_test run_unittests
+  fi
   run_test run_functionaltests
 fi
 run_test run_oldtests