Fixed pure ruby mrbgems can't compile and fixed build script wrong variable name

tasks/mruby_build.rake

@@ -20,7 +20,7 @@ module MRuby
     attr_accessor :ld, :ldflags, :libs
     attr_accessor :ar
     attr_writer :cxx, :cxxflags
-    attr_writer :objcc, :objccflags
+    attr_writer :objcc, :objcflags
     attr_writer :asm, :asmflags
     attr_accessor :gperf, :yacc
     attr_accessor :cat, :git
@@ -46,13 +46,13 @@ module MRuby
     end
 
     def cxx; @cxx || cc; end
-    def cxxflags; @cxxflags.empty? ? cflags : @cxxflags; end
+    def cxxflags; !@cxxflags || @cxxflags.empty? ? cflags : @cxxflags; end
 
     def objcc; @objcc || cc; end
-    def objccflags; @objccflags.empty? ? cflags : @objccflags; end
+    def objcflags; !@objcflags || @objcflags.empty? ? cflags : @objcflags; end
 
     def asm; @asm || cc; end
-    def asmflags; @asmflags.empty? ? cflags : @asmflags; end
+    def asmflags; !@asmflags || @asmflags.empty? ? cflags : @asmflags; end
 
     def ld; @ld || cc; end
 

tasks/mruby_gem_spec.rake

@@ -147,7 +147,7 @@ __EOF__
           build.compile_mruby f, rbfiles, "gem_mrblib_irep_#{funcname}" unless rbfiles.empty?
           f.puts "void mrb_#{funcname}_gem_init(mrb_state *mrb);"
           f.puts "void GENERATED_TMP_mrb_#{funcname}_gem_init(mrb_state *mrb) {"
-          f.puts "  mrb_#{funcname}_gem_init(mrb);" unless objs.empty?
+          f.puts "  mrb_#{funcname}_gem_init(mrb);" if objs != ["#{build_dir}/gem_init.o"]
           f.puts <<__EOF__ unless rbfiles.empty?
   mrb_load_irep(mrb, gem_mrblib_irep_#{funcname});
   if (mrb->exc) {