dlls/explorerframe: build tests with -D__WINESRC__

[Marvin]

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://newtestbot.winehq.org/JobDetails.pl?Key=2750

Your paranoid android.


=== wvista (32 bit nstc) ===
nstc.c:1934: Test failed: Got event 7, count 0
nstc.c:1936: Test failed: Got event 4, count 0
nstc.c:1949: Test failed: Got event 4, count 0