Fix integration test for ‘oni-cpp’

The output contains more than just the print statement in the test, but it ends
with the result.

test/integration/oni-cpp.bats

@@ -1,11 +1,11 @@
 #!/usr/bin/env bats
 
-@test "Opening a .cpp file loads oni-c++" {
+@test "Opening a .cpp file loads oni-cpp" {
     run emacs -batch -l package -f package-initialize \
         -visit test.cpp \
         -eval "(prin1 (featurep 'oni-cpp))"
 
     echo "$output"
 
-    [ "$output" = "t" ]
+    [[ "$output" == *"t" ]]
 }