Workaround for VC 19.42.34433

Suddenly it began to add `_ucrt_int_to_float` by the recent version.

Author: nobu

win32/mkexports.rb

@@ -122,6 +122,7 @@ def each_export(objs)
           elsif !l.sub!(/^(\S+) \([^@?\`\']*\)$/, '\1')
             next
           end
+          next if /\A__+ucrt_/ =~ l
         when /DLL/
           next unless l.sub!(/^\s*\d+\s+[[:xdigit:]]+\s+[[:xdigit:]]+\s+/, '')
         else