- introduce variable _BB_CONFIG_DEP to the new test harness.

This is used to see if given tests should be run (are available) or not.
  Print "UNTESTED: descr" if the applet or feature is not available.
- add _BB_CONFIG_DEP to existing new.tests
- move old grep test to new test infrastructure and add a few more test for
  grep.

testsuite/uniq.tests

@@ -9,6 +9,9 @@
 if [ ${#COMMAND} -eq 0 ]; then COMMAND=uniq; fi
 . testing.sh
 
+# Depends on uniq
+_BB_CONFIG_DEP=uniq
+
 # testing "test name" "options" "expected result" "file input" "stdin"
 #   file input will be file called "input"
 #   test can create a file "actual" instead of writing to stdout