block-mount: fsck.sh should only call pi_include() if dir /lib/functions/fsck exists.

block-mount: fsck.sh should only call pi_include() if dir /lib/functions/fsck exists.

/etc/functions.sh:pi_include() checks if the argument exists and prints
a warning if not. To prevent this warning if package block-mount is installed
but not package e2fsprogs, the script should check if this directory exists
before calling pi_include()

A wrong patch to suppress this warning was previously posted
with subject:
	[PATCH] Fix typo in name of to be included file

Signed-off-by: Mark Vels <mark.vels@team-embedded.nl>
SVN-Revision: 26503