README: Use distro packages, not CPAN

The XML::Simple and XML::SAX::Expat perl libraries are available as
Debian/Ubuntu packages.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/README b/README
index 638e5f1..12cc223 100644
--- a/README
+++ b/README
@@ -9,12 +9,10 @@
 
 1. Install Ubuntu 14.04 or Debian 7.5 64-bit.
 2. Install the packages necessary for the build:
-> sudo apt-get install cscope ctags libz-dev libexpat-dev libc6-dev-i386 gcc g++ git bison flex gcc-multilib g++-multilib
-3. Install PERL modules necessary for the build:
-> sudo cpan install XML::Simple XML::SAX::Expat
-4. Override the /bin/dash default shell configuration, you want to answer "no":
+> sudo apt-get install cscope ctags libz-dev libexpat-dev libc6-dev-i386 gcc g++ git bison flex gcc-multilib g++-multilib libxml-simple-perl libxml-sax-perl
+3. Override the /bin/dash default shell configuration, you want to answer "no":
 > sudo dpkg-reconfigure dash
-5. Continue with the clone, environment setup, and build as noted above.
+4. Continue with the clone, environment setup, and build as noted above.
 
 Building on *64-bit* Fedora systems
 ==========================================