mkexports.rb: flip-flop

* win32/mkexports.rb (Exports::Mswin#each_export): get rid of
  flip-flop warning.  [ruby-core:88147] [Bug #14946]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64095 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

win32/mkexports.rb

@@ -109,7 +109,11 @@ class Exports::Mswin < Exports
     objs = objs.collect {|s| s.tr('/', '\\')}
     filetype = nil
     objdump(objs) do |l|
-      if (filetype = l[/^File Type: (.+)/, 1])..(/^\f/ =~ l)
+      if filetype
+        if /^\f/ =~ l
+          filetype = nil
+          next
+        end
         case filetype
         when /OBJECT/, /LIBRARY/
           next if /^[[:xdigit:]]+ 0+ UNDEF / =~ l
@@ -130,6 +134,8 @@ class Exports::Mswin < Exports
           next
         end
         yield l.strip, is_data
+      else
+        filetype = l[/^File Type: (.+)/, 1]
       end
     end
     yield "strcasecmp", "msvcrt.stricmp"