msi: Simplify check for an empty string (PVS-Studio)

[Michael Stefaniuc]

On 11/05/2014 01:26 PM, Marvin wrote:
> Hi,
> 
> While running your changed tests on Windows, I think I found new failures.
> Being a bot and all I'm not very good at pattern recognition, so I might be
> wrong, but could you please double-check?
> Full results can be found at
> https://testbot.winehq.org/JobDetails.pl?Key=10031
> 
> Your paranoid android.
> 
> 
> === w2000pro (32 bit action) ===
> The test timed out
> 
> === wxppro (32 bit action) ===
> The test timed out
> 
> === wvistau64 (32 bit action) ===
> The test timed out
> 
> === w7u (32 bit action) ===
> The test timed out
> 
> === w8 (32 bit action) ===
> The test timed out
> 
> === wvistau64 (64 bit action) ===
> Failure running script in VM: timed out waiting for the child process

msi:action is renowned at timing out:
http://test.winehq.org/data/tests/msi:action.html

bye
	michael