vboxguestdrivers: add mount.vboxsf utility

:Release Notes:
The mount.vboxsf is a mount utility to share a folder between
Host OS and Emulator.

:Detailed Notes:
Emulator has only a small disk for data. but some applicatons may
need more space to store their data.
So emulator should offer a mount utility with existed vboxsf kernel
module to use a defined folder on Host OS.

:Testing Performed:
To mount shared folder in emulator, use the following command in
the terminal prompt.
mount -t vboxsf [name of shared folder] [mount point]

:QA Notes:

:Issue Addressed:
[GF-8867]Emulator needs to share a directory with a Host OS
[GF-11532]CCC: modify recipe for vboxguestdrivers

Open-webOS-DCO-1.0-Signed-off-by: Minjung Kim <mjane.kim@lge.com>

Change-Id: I8ac97b6b0736a147350f1b9cd975292ee6096601
Reviewed-on: https://g2g.palm.com/2853
Reviewed-by: Build Verification
Reviewed-by: Minjung Kim <mjane.kim@lge.com>
Tested-by: Minjung Kim <mjane.kim@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>