The option /Zc:wchar_t- prevented to use wchar_t as a built-in type
according to the C++ standard. In Visual C++ 6.0 and earlier, wchar_t
was not implemented as a built-in type, but was declared in wchar.h as
a typedef for unsigned short. Now, years later after the end of life
this outdated toolchain, there is no reason not to use native type.

The only issue could be the ABI compatibility. But on a quick look at
least, it looks like none of the mangled C++ symbols in the stable URE
interface actually depend on wchar_t.

We forgot to get rid of /Zc:wchar_t- in 5.1. Do that for LibreOffice
5.2, though.

Change-Id: I8d6b380660859efa44c83c830734978d31d756a0
Reviewed-on: https://gerrit.libreoffice.org/22589Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>