uclibc requires -D_GNU_SOURCE to be defined for it
to enable GNU extensions which CPU_SET/CPU_ZERO are
used by this package. So we add -D_GNU_SOURCE to
CFLAGS when compiling for uclibc.
(From OE-Core rev: fdbcf8eea9d83a8040157d8a5bb6febae5eb9a14)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>