uclibc wants to know value of __USE_GNU for certain
header prototypes to be enabled. So we move the config.h
header up in search list.
(From OE-Core rev: 086679cfbc30dba4af2f650984084195e5171b8f)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>