Rename libmruby stuff to avoid confusion

lib/mruby/build.rb

@@ -45,9 +45,11 @@ module MRuby
     include Rake::DSL
     include LoadGems
     attr_accessor :name, :bins, :exts, :file_separator, :build_dir, :gem_clone_dir
-    attr_reader :libmruby, :gems, :toolchains
+    attr_reader :libmruby_objs, :gems, :toolchains
     attr_writer :enable_bintest, :enable_test
 
+    alias libmruby libmruby_objs
+
     COMPILERS = %w(cc cxx objc asm)
     COMMANDS = COMPILERS + %w(linker archiver yacc gperf git exts mrbc)
     attr_block MRuby::Build::COMMANDS
@@ -81,7 +83,7 @@ module MRuby
         @mrbc = Command::Mrbc.new(self)
 
         @bins = []
-        @gems, @libmruby = MRuby::Gem::List.new, []
+        @gems, @libmruby_objs = MRuby::Gem::List.new, []
         @build_mrbtest_lib_only = false
         @cxx_exception_enabled = false
         @cxx_exception_disabled = false
@@ -327,6 +329,18 @@ EOS
       puts "================================================"
       puts
     end
+
+    def libmruby_static
+      libfile("#{build_dir}/lib/libmruby")
+    end
+
+    def libmruby_core_static
+      libfile("#{build_dir}/lib/libmruby_core")
+    end
+
+    def libraries
+      [libmruby_static]
+    end
   end # Build
 
   class CrossBuild < Build

lib/mruby/gem.rb

@@ -87,7 +87,7 @@ module MRuby
           fail "#{name || dir} required to set name, license(s) and author(s)"
         end
 
-        build.libmruby << @objs
+        build.libmruby_objs << @objs
 
         instance_eval(&@build_config_initializer) if @build_config_initializer
       end