Fix for bug 2283 (RVCT 4.0 support is missing from PDK 3.0.h) Have multiple extension sections in the bld.inf, one for each version of the compiler. The RVCT version building the tools will build the runtime libraries for its version, but make sure we extract all the other versions from zip archives. Also add the archive for RVCT4.

<?xml version="1.0" encoding="UTF-8"?>
<relnotes name="User HAL">
  <purpose>
    User side access to hardware via hardware abstraction.
  </purpose>
</relnotes>