postinst-intercepts, qemu.bbclass: fix segfaults in postinstalls

postinst-intercepts, qemu.bbclass: fix segfaults in postinstalls

Postinstalls that use qemu are throwing a segmentation fault when
building for qemux86-64 on a 64bit host (it might also happen for
qemux86 if building on a 32bit host but I didn't test). It looks like
qemu looks for ld.so.cache which is not found because it is generated
after rootfs_(rpm|ipk|deb)_do_rootfs is called and then it tries to load
libraries from the default paths (which are the host's). In order to
avoid this, pass the LD_LIBRARY_PATH explicitly to the target's dynamic
loader.

(From OE-Core rev: 48e8b613b3f5c7b1d917bf3147606d44072ce49e)

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