When building nativesdk recipes, we noticed paths going into .pc files
which should have been suppressed since these were standard library
search paths. pkgconfig-native sets these variables to sane values
for native recipes, we need it set to values for our specific library
paths in the nativesdk case.
Setting these values cleans up the .pc files and suppresses the paths.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
