Btrfs-progs: add static compile target

Btrfs-progs: add static compile target

Sometimes, when you least expect it, a static binary is what you need to
rescue your data... Or just get a good enough handle on things to make
it work again ;)

"make static" is a gift to you, dear user with filesystem problems!

Anyway, on a more serious note, changed the cflags and ldflags so that
we create a smaller binary, 1.1MB stripped on my 64 bit system
(2.7MB with debug data)

Signed-off-by: Ian Kumlien <pomac@demius.net>