* win32/setup.mak: $(APPEND) with some arguments insert a space before
  the arguments, so it causes error if the arguments are expected to be
  a macro definition.  this fix resolve the build error introduced at
  r48210.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48211 b2dd03c8-39d4-4d8f-98ff-823fe69b080e