Set lexer for VHDL language.

Conflicts:

	test/test_blob.rb

lib/linguist/languages.yml

@@ -1150,7 +1150,7 @@ Twig:
 
 VHDL:
   type: programming
-  lexer: Text only
+  lexer: vhdl
   primary_extension: .vhd
   extensions:
   - .vhd

test/fixtures/foo.vhd

@@ -0,0 +1,14 @@
+-- VHDL example file
+
+library ieee;
+use ieee.std_logic_1164.all;
+
+entity inverter is
+	port(a : in std_logic;
+	     b : out std_logic);
+end entity;
+
+architecture rtl of inverter is
+begin
+	b <= not a;
+end architecture;

test/test_blob.rb

@@ -287,6 +287,7 @@ class TestBlob < Test::Unit::TestCase
     assert_equal Language['Ruby'],        blob("script.rb").language
     assert_equal Language['Ruby'],        blob("wrong_shebang.rb").language
     assert_equal Language['Arduino'],     blob("hello.ino").language
+    assert_equal Language['VHDL'],        blob("foo.vhd").language
     assert_nil blob("octocat.png").language
 
     # .cls disambiguation
@@ -436,6 +437,7 @@ class TestBlob < Test::Unit::TestCase
     assert_equal Lexer['Scheme'], blob("dude.el").lexer
     assert_equal Lexer['Text only'], blob("README").lexer
     assert_equal Lexer['Tea'], blob("foo.tea").lexer
+    assert_equal Lexer['vhdl'], blob("foo.vhd").lexer
   end
 
   def test_shebang_script