Since r60696, WINVER is forced to _WIN32_WINNT_WIN2K. This has two problems:
- Vs8 (and before) does not define _WIN32_WINNT_WIN2K. It should be
replaced with 0x500.
- When WINVER is set to 0x500, vc6 gives a long warning because at the
time, windows nt 5.0 was only at beta stage. Moreover, there are other
clashes between winsock.h and winsock2.h, that show up when WINVER is 0x500.

To correct this, I propose:
- To replace _WIN32_WINNT_WIN2K and similar constants by their values.
- That 0x500 is not the required value, but the *maximum* value
necessary when targeting win2k. VC6 can set it to 0x400.

I'll try a patch later tonight.