libtool obtains the search path from /etc/ld.so.conf and hardcodes /usr/lib
and /lib. This results in host contamination and variable sets of RPATH
values ending up in binaries.
By exporting the correct values for all autotools recipes we avoid this.
(From OE-Core rev: 93e595d5c89ebacdb8d1e6fcfe6f58fe2d30de28)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>