package.bbclass: change RPATHs for cross-canadian binaries

package.bbclass: change RPATHs for cross-canadian binaries

When building the meta-toolchain, the binaries didn't get relocatable
RPATHs. They were hardcoded to the default path. Hence, if one had
already installed one SDK in the default path and one in another
location, the later toolchain's binaries would search and load libraries
from the first location, ending in a "Segmentation Fault".

[YOCTO #2927]

(From OE-Core rev: b40a03c43d5d9d738a9aa5b43b2ecfe74fc95018)

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>