(For real this time.  It turns out that 4 and 5 are different numbers.)

Bug 5858; fix on 0.2.3.12-alpha

This commit is completely mechanical; I used this perl script to make it:

 #!/usr/bin/perl -w -i.bak -p

 if (/^\s*\#/) {
     s/MS_WINDOWS/_WIN32/g;
     s/\bWIN32\b/_WIN32/g;
 }