Use cellar paths in tests

This lets `brew test` work when these are keg-only, etc. Also fix a
couple of typos and style things.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/autoconf.rb

@@ -6,22 +6,22 @@ class Autoconf < Formula
   mirror 'http://ftp.gnu.org/gnu/autoconf/autoconf-2.68.tar.gz'
   md5 'c3b5247592ce694f7097873aa07d66fe'
 
+  if MacOS.xcode_version.to_f < 4.3 or File.file? "/usr/bin/autoconf"
+    keg_only "Xcode (up to and including 4.2) provides (a rather old) Autoconf."
+  end
+
   def patches
     # force autoreconf to look for and use our glibtoolize
     DATA
   end
 
-  if MacOS.xcode_version.to_f < 4.3 or File.file? "/usr/bin/autoconf"
-    keg_only "Xcode (up to and including 4.2) provides (a rather old) Autoconf."
-  end
-
   def install
     system "./configure", "--disable-dependency-tracking", "--prefix=#{prefix}"
     system "make install"
   end
 
   def test
-    system "#{HOMEBREW_PREFIX}/bin/autoconf --version"
+    system "#{bin}/autoconf --version"
   end
 end
 

Formula/automake.rb

@@ -24,11 +24,6 @@ class Automake < Formula
   end
 
   def test
-    # This test will fail and we won't accept that! It's enough to just
-    # replace "false" with the main program this formula installs, but
-    # it'd be nice if you were more thorough. Test the test with
-    # `brew test automake`. Remove this comment before submitting
-    # your pull request!
-    system "#{HOMEBREW_PREFIX}/bin/automake --version"
+    system "#{bin}/automake --version"
   end
 end

Formula/libtool.rb

@@ -9,8 +9,8 @@ class Libtool < Formula
   mirror 'http://ftp.gnu.org/gnu/libtool/libtool-2.4.tar.gz'
   md5 'b32b04148ecdd7344abc6fe8bd1bb021'
 
-  if MacOS.xcode_version.to_f < 4.3 or File.file? "/usr/bin/libtoolize"
-    keg_only "Xcode (up to and including 4.2) provides (a rather old) Autoconf."
+  if MacOS.xcode_version.to_f < 4.3 or File.file? "/usr/bin/glibtoolize"
+    keg_only "Xcode (up to and including 4.2) provides (a rather old) Libtool."
   end
 
   def install
@@ -27,6 +27,6 @@ class Libtool < Formula
   end
 
   def test
-    system "#{HOMEBREW_PREFIX}/bin/glibtoolize --version"
+    system "#{bin}/glibtoolize --version"
   end
 end