Cleanup on doc/build-unix.txt

doc/build-unix.txt

@@ -28,7 +28,6 @@ Dependencies
  libdb4.8    Berkeley DB       Blockchain & wallet storage
  libboost    Boost             C++ Library
  miniupnpc   UPnP Support      Optional firewall-jumping support
- libqrencode QRCode generation Optional QRCode generation
 
 miniupnpc may be used for UPnP port mapping.  It can be downloaded from
 http://miniupnp.tuxfamily.org/files/.  UPnP support is compiled in and
@@ -37,13 +36,7 @@ turned off by default.  Set USE_UPNP to a different value to control this:
  USE_UPNP=0    (the default) UPnP support turned off by default at runtime
  USE_UPNP=1    UPnP support turned on by default at runtime
 
-libqrencode may be used for QRCode image generation. It can be downloaded
-from http://fukuchi.org/works/qrencode/index.html.en, or installed via
-your package manager. Set USE_QRCODE to control this:
- USE_QRCODE=0   (the default) No QRCode support - libqrcode not required
- USE_QRCODE=1   QRCode support enabled
-
-IPv6 support may be enabled by setting
+IPv6 support may be enabled by setting:
  USE_IPV6=1    Enable IPv6 support
 
 Licenses of statically linked libraries:
@@ -61,15 +54,27 @@ Versions used in this release:
 
 Dependency Build Instructions: Ubuntu & Debian
 ----------------------------------------------
+Build requirements:
  sudo apt-get install build-essential 
  sudo apt-get install libssl-dev
+
+for Ubuntu 12.04:
+ sudo apt-get install libboost-all-dev
+
+ db4.8 packages are available at:
+ https://launchpad.net/~bitcoin/+archive/bitcoin
+
+ Ubuntu precise has packages for libdb5.1-dev and libdb5.1++-dev,
+ but using these will break binary wallet compatibility, and is not recommended.
+
+for other Ubuntu & Debian:
  sudo apt-get install libdb4.8-dev 
  sudo apt-get install libdb4.8++-dev
- Boost 1.40+: sudo apt-get install libboost-all-dev
- or Boost 1.37: sudo apt-get install libboost1.37-dev
-sudo apt-get install libqrencode-dev
+ sudo apt-get install libboost1.37-dev
+ (If using Boost 1.37, append -mt to the boost libraries in the makefile)
 
-If using Boost 1.37, append -mt to the boost libraries in the makefile.
+Optional:
+ sudo apt-get install libminiupnpc-dev (see USE_UPNP compile flag)
 
 
 Dependency Build Instructions: Gentoo