FileUtils: Drop the QTC_CHECK for !endsWith(slash)

As exercised by the test directories as Utils::FileName are actually
supported. The resulting fileName() is empty.

Change-Id: Ie20ac58c1d0f416d711c8cc3281054c0d70c449e
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/fileutils.cpp

@@ -592,7 +592,6 @@ QString FileName::fileName(int pathComponents) const
     if (pathComponents < 0)
         return *this;
     const QChar slash = QLatin1Char('/');
-    QTC_CHECK(!endsWith(slash));
     int i = lastIndexOf(slash);
     if (pathComponents == 0 || i == -1)
         return mid(i + 1);