Remove embedded atf-src and enforce atf >= 0.20 + kyua as execution engine

.gitignore

@@ -27,35 +27,6 @@ gen.dSYM/
 .deps/
 .dirstamp
 .libs/
-unit/atf-src/atf-c++/atf-c++.pc
-unit/atf-src/atf-c/atf-c.pc
-unit/atf-src/atf-c/defs.h
-unit/atf-src/atf-c/detail/process_helpers
-unit/atf-src/atf-config/atf-config
-unit/atf-src/atf-report/atf-report
-unit/atf-src/atf-report/fail_helper
-unit/atf-src/atf-report/misc_helpers
-unit/atf-src/atf-report/pass_helper
-unit/atf-src/atf-run/atf-run
-unit/atf-src/atf-run/bad_metadata_helper
-unit/atf-src/atf-run/expect_helpers
-unit/atf-src/atf-run/misc_helpers
-unit/atf-src/atf-run/pass_helper
-unit/atf-src/atf-run/several_tcs_helper
-unit/atf-src/atf-run/zero_tcs_helper
-unit/atf-src/atf-sh/atf-check
-unit/atf-src/atf-sh/atf-sh
-unit/atf-src/atf-sh/misc_helpers
-unit/atf-src/atf-version/atf-version
-unit/atf-src/atf-version/revision.h
-unit/atf-src/atf-version/revision.h.stamp
-unit/atf-src/bconfig.h
-unit/atf-src/bootstrap/atconfig
-unit/atf-src/doc/atf.7
-unit/atf-src/stamp-h1
-unit/atf-src/test-programs/c_helpers
-unit/atf-src/test-programs/cpp_helpers
-unit/atf-src/test-programs/sh_helpers
 # ccc-analyzer store its results in .plist directories
 *.plist/
 *~