msvcrt/tests: Enable compilation 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=3213

Your paranoid android.


=== wxppro (32 bit file) ===
file.c:1417: Test failed: bad position 0 expecting 8
file.c:1419: Test failed: Couldn't read back the data
file.c:1987: Test failed: i 0, got 0
file.c:1990: Test failed: expected to read 'Hello world', got ''
file.c:1987: Test failed: i 1, got 0
file.c:1990: Test failed: expected to read 'Hello world', got ''
file.c:1987: Test failed: i 2, got 0
file.c:1990: Test failed: expected to read 'Hello world', got ''
file.c:2024: Test failed: fread() returned 0: ferror=0
file.c:2027: Test failed: got '' expected 'Hello worldHello worldHello world'