When running make vs2013-ide-integration on windows, the manifest
targets cause duplicate library/executable entries to be output in
the Visual Studio solution files, causing errors.

Change-Id: I6b0ce38a3ba84f7f54741e4974264e2c4c7b201a
Reviewed-on: https://gerrit.libreoffice.org/18719Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>