Plus this will save some memory footprint.

This is slightly modified version of patch from Lubos Lunak
<llunak@suse.cz>.

This fixes downstream bugs:
https://bugs.gentoo.org/show_bug.cgi?id=394533
https://bugs.launchpad.net/bugs/925049

We just need to append '2' on the 2nd field with identical name, not '1'.
This alone fixes the import problem.

Old code used Table Seek/Next followed by GetCurKey() that returned -1 (or
some such? anyway) if after the last element, comparing with another key.
Replacement code did not check for valid iterators.

Crash happened when changing the locale within the number formatter and
obtaining the default currency format. May also have happened when changing
the default locale and documents using a number formatter were open.

due to use of ImplInheritanceHelper2 SfxStyleSheet needs a default ctor, though
its never called. rearrange things a little so we can have an empty ctor
without pulling in a bunch of code which is never executed