Don't stop on os.makedirs when making vs2012-ide-integration

At the moment it always stops on folders that already exists. See
https://bugs.freedesktop.org/show_bug.cgi?id=70414#c18 and the following
comments for example of the error messages that I face without this patch.

Change-Id: I1a1f337872ce3a817d425ff10255e3ae9a73c1a2
Reviewed-on: https://gerrit.libreoffice.org/10062
Tested-by: Fridrich Strba <fridrich@documentfoundation.org>
Reviewed-by: Fridrich Strba <fridrich@documentfoundation.org>