msvcrt: fix utime to correctly handle a NULL-pointer with tests (try 2)

[Louis Lenders]

Hi, i merged patch + test to avoid test failure. Hope it's ok now, if not, i'd like to hear what i could improve

this fixes bug http://bugs.winehq.org/show_bug.cgi?id=25156

the reason for dynamically loading utime with GetProcAddress is that there was a problem crosscompiling the testexecutable. I got a link error, seems to be a problem with mingw according to googl
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