Fix links to headings

A previous change made the header's id be fully referenced (for the sidebar I believe) but this broke links to them.
This fixes the issue.

lib/rdoc/markup/to_html_crossref.rb

@@ -153,7 +153,7 @@ class RDoc::Markup::ToHtmlCrossref < RDoc::Markup::ToHtml
             ref.sections.any? { |section| label == section.title } then
         path << "##{label}"
       else
-        path << "#label-#{label}"
+        path << "##{ref.aref}-label-#{label}"
       end if label
 
       "<a href=\"#{path}\">#{text}</a>"

test/rdoc/test_rdoc_markup_to_html_crossref.rb

@@ -19,7 +19,7 @@ class TestRDocMarkupToHtmlCrossref < XrefTestCase
 
   def test_convert_CROSSREF_label
     result = @to.convert 'C1@foo'
-    assert_equal para("<a href=\"C1.html#label-foo\">foo at <code>C1</code></a>"), result
+    assert_equal para("<a href=\"C1.html#class-C1-label-foo\">foo at <code>C1</code></a>"), result
 
     result = @to.convert 'C1#m@foo'
     assert_equal para("<a href=\"C1.html#method-i-m-label-foo\">foo at <code>C1#m</code></a>"),
@@ -28,12 +28,12 @@ class TestRDocMarkupToHtmlCrossref < XrefTestCase
 
   def test_convert_CROSSREF_label_period
     result = @to.convert 'C1@foo.'
-    assert_equal para("<a href=\"C1.html#label-foo\">foo at <code>C1</code></a>."), result
+    assert_equal para("<a href=\"C1.html#class-C1-label-foo\">foo at <code>C1</code></a>."), result
   end
 
   def test_convert_CROSSREF_label_space
     result = @to.convert 'C1@foo+bar'
-    assert_equal para("<a href=\"C1.html#label-foo+bar\">foo bar at <code>C1</code></a>"),
+    assert_equal para("<a href=\"C1.html#class-C1-label-foo+bar\">foo bar at <code>C1</code></a>"),
                  result
   end
 
@@ -104,7 +104,7 @@ class TestRDocMarkupToHtmlCrossref < XrefTestCase
   def test_convert_RDOCLINK_rdoc_ref_label
     result = @to.convert 'rdoc-ref:C1@foo'
 
-    assert_equal para("<a href=\"C1.html#label-foo\">foo at <code>C1</code></a>"), result,
+    assert_equal para("<a href=\"C1.html#class-C1-label-foo\">foo at <code>C1</code></a>"), result,
                  'rdoc-ref:C1@foo'
   end