[ruby-cvs:63214] nobu:r56049 (trunk): mkmf.rb: fix up r56047

[nobu at ruby-lang.org]

nobu	2016-08-31 20:20:45 +0900 (Wed, 31 Aug 2016)

  New Revision: 56049

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=56049

  Log:
    mkmf.rb: fix up r56047
    
    * lib/mkmf.rb (create_makefile): TARGET_SO_DIR should not be the
      root directory when sodir is empty.

  Modified files:
    trunk/lib/mkmf.rb