merger takes MC file names as UTF16 names. (#11506)

merger takes MC file names as UTF16 names. (#11506)

There were problems with:
1. Arabick and Japanese symbols in CLR_SH;
2. Long MC names.

We didn't see these problem before, because we moved all MC files and
renamed them with short numbers names.
Now if we want to:
1. avoid  MC files copying;
2. save information that is encoded in this names for spmi diff between
different collections
we want this fix.