app-shells/bash: show full cwd for root user

app-shells/bash: show full cwd for root user

Though the first declaration of PS1 in this file uses \w uniformly for
root and non-root, the two subsequent ones inconsistently do not. Thus, a
normal user is able to see clearly where he is in the file system,
whereas the root user -- who should have this sort of visibility -- does
not, since \W (upper-case) is used instead. It seems clear that this
difference is just the result of an old bug; \w for both user types is
clearly more reasonable. This patch fixes things up as such.

Signed-off-by: Jason A. Donenfeld <zx2c4@gentoo.org>