lsbtest: add option --ignoreos to rpm install command

lsbtest: add option --ignoreos to rpm install command

After change to the rpm4, the rpm packages in lsbtest, such as:

    lsb-setup-4.1.0-1.noarch.rpm
    lsb-dist-checker-5.0.0.1-1.x86_64.rpm
    ......
    lsb-cmdchk-5.0.3-1.x86_64.rpm

When install above rpm packages, the error log appears:

    package lsb-setup-4.1.0-1.noarch is intended for a different operating system
    ......

So we should add option "--ignoreos" to the rpm install command in LSB_Test.sh
in ./meta/recipes-extended/lsb/lsbtest directory. In this way we can make sure
the correct installation of those rpm packages.

The YOCTO bug #11224 didn't create logs, this is because the above test rpm
packages didn't install.

[YOCTO #11224]

Signed-off-by: Dengke Du <dengke.du@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>