Begin to move file system related parts out of kernel.c
Rewrite strlen and strcmp with C.

	modified:   str.c

    strlen - BSD implementation, see
    http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/string/strlen.c?rev=1.7;content-type=text%2Fplain;only_with_tag=MAIN

    strcmp - see
    http://clc-wiki.net/wiki/C_standard_library:string.h:strcmp
Not to run queue_str_task1 and queue_str_task2
strncmp in C

ref: http://svnweb.freebsd.org/base/head/lib/libc/string/strncmp.c?revision=251069&view=markup