conf.enable_test makes conf.build_mrbtest_lib_only obsolete

we were using conf.build_mrbtet_lib_only for detecting whether to run
tests on that build, but now with conf.enable_test we can use that
instead

Author: hone

build_config.rb

@@ -18,8 +18,6 @@ def gem_config(conf)
 MRuby::Build.new('x86_64-pc-linux-gnu') do |conf|
   toolchain :gcc
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -30,8 +28,6 @@ def gem_config(conf)
     cc.flags << "-m32"
   end
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -47,8 +43,6 @@ def gem_config(conf)
   conf.build_target     = 'x86_64-pc-linux-gnu'
   conf.host_target      = 'x86_64-apple-darwin14'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -64,8 +58,6 @@ def gem_config(conf)
   conf.build_target     = 'i386-pc-linux-gnu'
   conf.host_target      = 'i386-apple-darwin14'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -82,8 +74,6 @@ def gem_config(conf)
   conf.build_target     = 'x86_64-pc-linux-gnu'
   conf.host_target      = 'x86_64-w64-mingw32'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -100,7 +90,5 @@ def gem_config(conf)
   conf.build_target     = 'i686-pc-linux-gnu'
   conf.host_target      = 'i686-w64-mingw32'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end

mrblib/setup.rb

@@ -128,8 +128,6 @@ def gem_config(conf)
 MRuby::Build.new('x86_64-pc-linux-gnu') do |conf|
   toolchain :gcc
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -140,8 +138,6 @@ def gem_config(conf)
     cc.flags << "-m32"
   end
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -157,8 +153,6 @@ def gem_config(conf)
   conf.build_target     = 'x86_64-pc-linux-gnu'
   conf.host_target      = 'x86_64-apple-darwin14'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -174,8 +168,6 @@ def gem_config(conf)
   conf.build_target     = 'i386-pc-linux-gnu'
   conf.host_target      = 'i386-apple-darwin14'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -192,8 +184,6 @@ def gem_config(conf)
   conf.build_target     = 'x86_64-pc-linux-gnu'
   conf.host_target      = 'x86_64-w64-mingw32'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 
@@ -210,8 +200,6 @@ def gem_config(conf)
   conf.build_target     = 'i686-pc-linux-gnu'
   conf.host_target      = 'i686-w64-mingw32'
 
-  conf.build_mrbtest_lib_only
-
   gem_config(conf)
 end
 BUILD_CONFIG_RB