Blind fix for -Werror,-Wunused-variable on macOS

...after c40ef4d1 "workaround jenkins failure on
OSX".  Probably better to keep executing the code under test than to #if-out the
whole block.

Change-Id: I83c21c532cd69f72834e4a242f767cca419b04ea

editeng/qa/unit/core-test.cxx

@@ -1895,6 +1895,8 @@ void Test::testHoriAlignIgnoreTrailingWhitespace()
 // this keeps failing on OSX with a value of 4495
 #if !defined(MACOSX)
         CPPUNIT_ASSERT_DOUBLES_EQUAL(static_cast<long>(4527), pLine->GetStartPosX(), 10);
+#else
+        (void) pLine; // avoid -Wunused-variable
 #endif
     }