hdf5

[svn-r15128] Purpose: Make Windows threadsafe debug message more useful

Description:
On Linux-like systems, we can get the ID of the current thread through a pthread_self.  However on Windows, the return cannot be cast as a threadID, so we simply couldn't get the ID.  Previously we simply gave up and printed a message that we couldn't get an ID.  Instead, though, we can use the Windows-specific call to GetCurrentThreadId(), which achieves the same goal.  This way we can provide better debug output with threadsafe features.

Tested:
VS2005 on WinXP
VS.NET on WinXP
(other platforms not tested because change is within _WIN32 ifdef)