libyang: Fix install conflict when enable multilib.

Error: Transaction test error:
  file /usr/include/libyang/config.h conflicts between attempted installs of libyang-dev-2.1.55-r0.core2_64 and lib32-libyang-dev-2.1.55-r0.i686

The differences of config.h are as follows:
@@ -27,8 +27,8 @@
 /** plugins */
 #define LYPLG_SUFFIX ".so"
 #define LYPLG_SUFFIX_LEN (sizeof LYPLG_SUFFIX - 1)
-#define LYPLG_TYPE_DIR "/usr/lib/libyang/types"
-#define LYPLG_EXT_DIR "/usr/lib/libyang/extensions"
+#define LYPLG_TYPE_DIR "/usr/lib64/libyang/types"
+#define LYPLG_EXT_DIR "/usr/lib64/libyang/extensions"

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-extended/libyang/libyang_2.1.55.bb

@@ -16,7 +16,7 @@ SRC_URI = "git://github.com/CESNET/libyang.git;branch=master;protocol=https \
 S = "${WORKDIR}/git"
 
 # Main dependencies
-inherit cmake pkgconfig lib_package ptest
+inherit cmake pkgconfig lib_package ptest multilib_header
 DEPENDS = "libpcre2"
 DEPENDS += "${@bb.utils.contains('PTEST_ENABLED', '1', 'cmocka', '', d)}"
 
@@ -30,6 +30,10 @@ do_compile:prepend () {
     fi
 }
 
+do_install:append () {
+        oe_multilib_header  libyang/config.h
+}
+
 do_install_ptest () {
     install -d ${D}${PTEST_PATH}/tests
     cp -f ${B}/tests/utest_* ${D}${PTEST_PATH}/tests/