[package] block-mount base-files: Added additional check to pi_include to ensure...

[package] block-mount base-files:  Added additional check to pi_include to ensure that a directory used with pi_include actually contains files matching the souring pattern because if not the shell dies due to an empty string in for statement.  Added /lib/functions/fsck as an empty dir to block-mount.  This combination fixes a warning which generates a lot of bug reports, without panicking the kernel like the last attempt.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@26479 3c298f89-4303-0410-b956-a3cf2f4a3e73