For some applications the shortcut's icon points to a .exe file which in
fact contains a .ico file. This means open_icon() cannot rely on the
file extension.  Also reject icon streams that don't actually contain a
valid icon and use the next source as a fallback.

msi: Handle errors from IStorage_CreateStream instead of trying to open the stream first in msi_commit_streams.

msi: Fix the case where the summary information stream is already open in MsiGetSummaryInformationW.