packagegroup-core-standalone-sdk-target: add kernel headers

In most cases, kernel headers need to be appended to SDK,
so it's better to add it into SDK by default.

Signed-off-by: Kazuhiro Hayashi <kazuhiro3.hayashi@toshiba.co.jp>

recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bb

@@ -14,6 +14,7 @@ RDEPENDS_${PN} = "\
     libatomic-dev \
     libstdc++ \
     libstdc++-dev \
+    linux-libc-headers-base-dev \
     ${LIBC_DEPENDENCIES} \
     "