Update libsass to master + other fixes

Updates libsass to master ([d225a09a](https://github.com/sass/libsass/tree/d225a09a152050d569c077f97bb944c8dc819d6f)) to incorporate fixes for:

1. The :not selector. Fixes #91. sass/libsass#2697
2. Default precision changed to 10. sass/libsass#2716
3. Now builds with `cc` instead of hard-coding `gcc`. sass/libsass#2707
4. Building on Linux and Solaris. sass/libsass#2720

Also:
1. Adds Windows RubyInstaller compilation support via `rake-compiler`. Fixes #18.
2. Fixes `load_paths` separator on Windows. Fixes #93.
3. Changes the location of `libsass.so` from `ext/` to `lib/`. Fixes #95.

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "ext/libsass"]
 	path = ext/libsass
-  url = git://github.com/sass/libsass.git
+	url = git://github.com/sass/libsass.git

README.md

@@ -6,7 +6,7 @@ This gem combines the speed of `libsass`, the [Sass C implementation](https://gi
 
 ### libsass Version
 
-[3.5.2](https://github.com/sass/libsass/releases/tag/3.5.2)
+[d225a09a](https://github.com/sass/libsass/commit/d225a09a152050d569c077f97bb944c8dc819d6f)
 
 ## Installation
 

Rakefile

@@ -4,12 +4,17 @@ rescue LoadError
   puts 'Cannot load bundler/gem_tasks'
 end
 
-require 'tasks/libsass'
-
 task default: :test
 
+require 'rake/extensiontask'
+Rake::ExtensionTask.new do |ext|
+  ext.name = 'libsass'
+  ext.ext_dir = 'ext'
+  ext.lib_dir = 'lib/sassc'
+end
+
 desc "Run all tests"
-task test: 'libsass:compile' do
+task test: 'compile:libsass' do
   $LOAD_PATH.unshift('lib', 'test')
   Dir.glob('./test/**/*_test.rb') { |f| require f }
 end

ext/extconf.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+gem_root = File.expand_path('..', __dir__)
+libsass_dir = File.join(gem_root, 'ext', 'libsass')
+
+File.write 'Makefile', <<-MAKEFILE
+ifndef DESTDIR
+	LIBSASS_OUT = #{gem_root}/lib/sassc/libsass.so
+else
+	LIBSASS_OUT = $(DESTDIR)$(PREFIX)/libsass.so
+endif
+
+SUB_DIR := #{libsass_dir}
+SUB_TARGET := lib/libsass.so
+
+libsass.so: #{'clean ' if ENV['CLEAN']}| $(SUB_DIR)
+	$(MAKE) -C '$(SUB_DIR)' lib/libsass.so
+	cp '$(SUB_DIR)/lib/libsass.so' libsass.so
+
+install: libsass.so
+	cp libsass.so '$(LIBSASS_OUT)'
+
+$(SUB_DIR):
+	cd '#{gem_root}'
+	git submodule update --init
+
+clean: | $(SUB_DIR)
+	$(MAKE) -C '$(SUB_DIR)' clean
+	rm -f '$(LIBSASS_OUT)' libsass.so
+
+.PHONY: clean install
+MAKEFILE

lib/sassc/engine.rb

@@ -133,7 +133,7 @@ def output_style
 
     def load_paths
       paths = @options[:load_paths]
-      paths.join(":") if paths
+      paths.join(File::PATH_SEPARATOR) if paths
     end
   end
 end

lib/sassc/native.rb

@@ -8,7 +8,7 @@ module Native
 
     spec = Gem.loaded_specs["sassc"]
     gem_root = spec.gem_dir
-    ffi_lib "#{gem_root}/ext/libsass/lib/libsass.so"
+    ffi_lib "#{gem_root}/lib/sassc/libsass.so"
 
     require_relative "native/sass_value"
 

sassc.gemspec

@@ -23,13 +23,15 @@ Gem::Specification.new do |spec|
 
   spec.require_paths = ["lib"]
 
-  spec.extensions    = ["ext/Rakefile"]
+  spec.platform      = Gem::Platform::RUBY
+  spec.extensions    = ["ext/extconf.rb"]
 
   spec.add_development_dependency "minitest", "~> 5.5.1"
   spec.add_development_dependency "minitest-around"
   spec.add_development_dependency "test_construct"
   spec.add_development_dependency "pry"
   spec.add_development_dependency "bundler"
+  spec.add_development_dependency "rake-compiler"
 
   spec.add_dependency "rake"
   spec.add_dependency "ffi", "~> 1.9.6"

test/engine_test.rb

@@ -88,7 +88,7 @@ def test_precision_not_specified
 SCSS
       expected_output = <<-CSS
 .foo {
-  baz: 0.33333; }
+  baz: 0.3333333333; }
 CSS
       output = Engine.new(template).render
       assert_equal expected_output, output

test/native_test.rb

@@ -11,7 +11,7 @@ module NativeTest
 
     class General < MiniTest::Test
       def test_it_reports_the_libsass_version
-        assert_equal "3.5.2", Native.version
+        assert_equal "3.5.2-87-gd225", Native.version
       end
     end