I add testsuite for grep.

It can test grep's option basically and I think it can help to check progress of development.
Clean up grep.test to use "infile" properly, and not try to work around the $PATH behavior of scripts/test.sh. Tested with both TEST_HOST=1 and normal.
Found the fault. My method of -w fails sans -E, so I just disallow it.
Kernel build never uses -w sans -E anyhow.
Cleanup grep: help text, whitespace, add parentheses.
ls --color should depend on LS in menuconfig.
Need to specify bool for CP_MV_MORE config symbol to avoid warnings.