echo: fix regression ("echo" with no arguments didn't print newline.

echo: fix regression ("echo" with no arguments didn't print newline.
echo: use fputs if no options are given. Code growth ~15 bytes.

Old:
# time ./busybox find $bigdir -exec echo {} \; >/dev/null
real    0m2.038s
user    0m0.761s
sys     0m0.953s

New:
# time ./busybox find $bigdir -exec echo {} \; >/dev/null
real    0m1.781s
user    0m0.781s
sys     0m0.939s

For comparison: without NOFORK:
# time find $bigdir -exec echo {} \; >/dev/null
real    1m51.129s
user    0m38.442s
sys     1m3.350s