Makefile.sub: need suffix

* win32/Makefile.sub: fix missing suffix of user32.lib.
  [Bug #14422]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62630 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

win32/Makefile.sub

@@ -866,7 +866,7 @@ s,@CPPFLAGS@,$(CPPFLAGS),;t t
 s,@CXXFLAGS@,$(CXXFLAGS),;t t
 s,@FFLAGS@,$(FFLAGS),;t t
 s,@LDFLAGS@,$(LDFLAGS),;t t
-s,@LIBS@,user32,;t t
+s,@LIBS@,user32.lib,;t t
 s,@MAINLIBS@,$(MAINLIBS),;t t
 s,@exec_prefix@,$${prefix},;t t
 s,@prefix@,$(prefix),;t t