fix race conditions, tests and some invalid return values

fix race conditions, tests and some invalid return values

Since the current winpr implementation for overlapped operations is
incomplete and buggy, all affected functions will now fail if they are
called with a set FILE_FLAG_OVERLAPPED flag or a non-null pointer to
a OVERLAPPED structure.

winpr/nt:
- use proper one-time initialization on win32
- fix TestNtCreateFile
- fix broken/incomplete _RtlAnsiStringToUnicodeString
- unimplemented functions return appropriate error codes

winpr/pipe:
- improved TestPipeCreateNamedPipe
- rewrite the completely broken TestPipeCreateNamedPipeOverlapped test

rdtk:
- improve test and don't blindly return success

winpr/synch:
- fix race condition in TestSynchTimerQueue

winpr/ssspi:
- fix TestEnumerateSecurityPackages printf output
- fix TestQuerySecurityPackageInfo printf output

winpr/environment:
- fix GetEnvironmentStrings printf output

winpr/comm:
- unimplemented functions return appropriate error codes

winpr/io:
- unimplemented functions return appropriate error codes

winpr/thread:
- implement SwitchToThread() via sched_yield()