postgresql: tcl is optional

Closes Homebrew#21099.

Library/Formula/postgresql.rb

@@ -5,6 +5,11 @@ class Postgresql < Formula
  url 'http:https://ftp.postgresql.org/pub/source/v9.2.4/postgresql-9.2.4.tar.bz2'
  sha1 '75b53c884cb10ed9404747b51677358f12082152'
 
+ option '32-bit'
+ option 'no-perl', 'Build without Perl support'
+ option 'no-tcl', 'Build without Tcl support'
+ option 'enable-dtrace', 'Build with DTrace support'
+
  depends_on 'readline'
  depends_on 'libxml2' if MacOS.version <= :leopard # Leopard libxml is too old
  depends_on 'ossp-uuid' => :recommended
@@ -13,10 +18,6 @@ class Postgresql < Formula
  conflicts_with 'postgres-xc',
  :because => 'postgresql and postgres-xc install the same binaries.'
 
- option '32-bit'
- option 'no-perl', 'Build without Perl support'
- option 'enable-dtrace', 'Build with DTrace support'
-
  fails_with :clang do
  build 211
  cause 'Miscompilation resulting in segfault on queries'
@@ -43,14 +44,14 @@ def install
  --with-ldap
  --with-openssl
  --with-pam
- --with-tcl
  --with-libxml
  --with-libxslt
  ]
 
  args << "--with-ossp-uuid" if build.with? 'ossp-uuid'
  args << "--with-python" if build.with? 'python'
  args << "--with-perl" unless build.include? 'no-perl'
+ args << "--with-tcl" unless build.include? 'no-tcl'
  args << "--enable-dtrace" if build.include? 'enable-dtrace'
 
  if build.with? 'ossp-uuid'