Merge pull request #2830 from hiroshiyui/mirb-termcap-compat

Remove the unused libterminfo detection code.

mrbgems/mruby-bin-mirb/mrbgem.rake

@@ -10,8 +10,6 @@ MRuby::Gem::Specification.new('mruby-bin-mirb') do |spec|
         if spec.build.cc.search_header_path 'termcap.h'
           if MRUBY_BUILD_HOST_IS_CYGWIN then
             spec.linker.libraries << 'ncurses'
-          elsif spec.linker.has_library('libterminfo') then
-            spec.linker.libraries << 'terminfo'
           else
             spec.linker.libraries << 'termcap'
           end