QLibrary: remove dead check

The variable `i` is initially `suffixPos + 1` and is then incremented
further. It therefore can never be equal to `suffixPos` (ints don't
overflow, that would be UB, and suffixPos doesn't change its value),
so don't check for that.

Change-Id: I3870ddf6ee550cad6c24fececf2a0b662a33d750
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/plugin/qlibrary.cpp

@@ -707,8 +707,7 @@ bool QLibrary::isLibrary(const QString &fileName)
 
     bool valid = suffixPos != -1;
     for (int i = suffixPos + 1; i < suffixes.count() && valid; ++i)
-        if (i != suffixPos)
-            (void)suffixes.at(i).toInt(&valid);
+        (void)suffixes.at(i).toInt(&valid);
     return valid;
 #endif
 }