[PATCH v3] rtems-tool DAWRF support with coverage changes

[Chris Johns]

Hi,

This is the 3rd version of the DWARF support for the RTEMS Tools project.

The DWARF support is:

 - DWARF source and line number support with a C++ addr2line test tool.
 - DWARF support for functions in complication units.
 - Add rtems-addr2line as a DWARF debug and test tool.

Covar has been updated to load the symbols from ELF and to perform
source line look up by address.

I have made some changes to coverage support in `rtems-test` so the
development build of covoar is used rather than one in the path. I have
cleaned up some of the python code and added trace control to contain the 
trace output from covoar.

My personal repo has the patches ready to use:

 https://git.rtems.org/chrisj/rtems-tools.git/?h=dwarf-types

Thanks
Chris