Add and use 'localedir' variable

This avoids the hardcoding of ${libdir}/locale which is all over the place,
and will facilitate use of ${exec_prefix}/lib/locale instead of
${libdir}/locale.

This doesn't actually change any output at this time. Verified this with
buildhistory against the packages produced from core-image-base.

(From OE-Core rev: b744f4cc2912334b8493a89525fd02af8e9b8edf)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/bitbake.conf

@@ -40,6 +40,7 @@ export libdir = "${exec_prefix}/${baselib}"
 export includedir = "${exec_prefix}/include"
 export oldincludedir = "${exec_prefix}/include"
 export systemd_unitdir = "${base_libdir}/systemd"
+localedir = "${libdir}/locale"
 
 # Linkage between native/cross/nativesdk layouts
 base_bindir_native = "/bin"