Yet another one undefined comparison of 'const' and a 'non-const' iterators

Fixes:
    no match for ‘operator!=’ in ‘i != std::vector<_Tp, _Alloc>::rend() [with _Tp = rtl::OUString, _Alloc = std::allocator<rtl::OUString>]()’

Change-Id: I7b4ba07ebe51c73893a3d6b77dcf5681b7638efb
Signed-off-by: Stephan Bergmann <sbergman@redhat.com>

unoidl/source/sourceprovider-parser.y

@@ -261,7 +261,7 @@ unoidl::detail::SourceProviderEntity * findEntity_(
     assert(name != 0);
     OUString n;
     if (!name->startsWith(".", &n)) {
-        for (std::vector<OUString>::const_reverse_iterator i(data->modules.rbegin());
+        for (std::vector<OUString>::reverse_iterator i(data->modules.rbegin());
              i != data->modules.rend(); ++i)
         {
             n = *i + "." + *name;