Feature 2930: Eliminate hardcoded /bin/echo in acceptance tests

To improve cross-platform compatibility, eliminates acceptance test path
hardcoding of /bin/echo, as well as adjacent "mkdir" an "ln" commands in
10_files/02_maintain/staging/copy-select-link-dereference.cf, taking
advantage of the mechanism in the "G" bundle which finds the correct
local-platform paths for a list of common commands.
Replace hardcoded command paths in acceptance tests with $(G.cmd)

The "G" bundle provides full path names for various commands, in order
to eliminate the need to hard code pathnames in the acceptance tests.
Some older operating systems may have Perl installed in /usr/local/bin,
for example.

This commit updates all acceptance tests to make use of the $(G.cmd)
variables for each of the listed commands in order to eliminate
hardcoding of command paths in order to increase cross-platform
compatibility.
Add default.cf.sub input in support of $(G) references

The two affected files did not include the default.cf.sub file
needed to support the global common "G" bundle which is
referenced.
Merge pull request #750 from mvpel/feature_2930

Feature 2930: Eliminate hardcoded paths in acceptance tests