CI: Add support for coverage processing.

Enable coverage with `./tests/CI/buildAsterisk.sh --coverage`.  This
will cause Asterisk to be compiled with coverage support.  It also
initializes 'before' coverage data for all sources.  Accept
--tested-only to disable modules which are not run by any test.
Enabling coverage also sets tested-only true by default.  To build
everything with coverage enabled use `--coverage --tested-only=0`.

./tests/CI/processCoverage.sh is used to process the coverage and
generate HTML reports.

Fix utils/check_expr2 which failed to compiled with coverage enabled.

Add status output 5 times per stage of astobj2_test_perf to ensure
remote CLI does not timeout when compiled with coverage.  Remote CLI
disconnects if no output is received for 60 seconds.  When coverage is
enabled it takes about 70 seconds for my laptop to run the stages of
this test, so with the change a message is printed every 14 seconds.

Change-Id: I890f7d5665087426ad7d3e363187691b9afc2222