Two more assembler goodies: strchr() and strlen().

NetBSD has an even more optimized strlen().  According to the
comment at the top it originated in 'The PowerPC Compiler Writer's
Guide', by Steve Hoxey, Faraydon Karim, Bill Hay and Hank Warren.

(http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/arch/powerpc/string/strlen.S?rev=1.2)

However, it would have been way too much work to convert the powerpc
assembly source into qa(1) source.

In any case, these ones should be faster than the C versions from
the libc/port directory.

-Tad