[test suite] exclude /usr/include/* files from lcov coverage analysis
[test suite] exercise client rc file ask overwrite feature via popen()
[test suite] add --profile-coverage-init to recompile and remove old .gcov and .gcda files
[test suite] add coverage test for client -M legacy truncated key
[test suite] additional critical var popen() tests
[test suite] add long_spa.key file