update_font_cache: update script for multilib

Packages which inherit fontcache.bbclass call postinstall script
update_font_cache. And in update_font_cache, it calls ${bindir}/fc-cache
by qemuwrapper. When multilib is enabled, both packages foo and lib32-foo
will call ${bindir}/fc-cache and one of them will fail to run obviously.

Duplicate install file fc-cache to ${libexecdir} with ${MLPREFIX} and
call proper fc-cache in update_font_cache.

(From OE-Core rev: 53d8625732b0c8416e367d5eef43863ec2065433)

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-graphics/fontconfig/fontconfig_2.12.6.bb

@@ -35,9 +35,15 @@ do_configure_prepend() {
     rm -f ${S}/src/fcobjshash.h ${S}/src/fcobjshash.gperf
 }
 
+do_install_append_class-target() {
+    # duplicate fc-cache for postinstall script
+    mkdir -p ${D}${libexecdir}
+    ln ${D}${bindir}/fc-cache ${D}${libexecdir}/${MLPREFIX}fc-cache
+}
+
 PACKAGES =+ "fontconfig-utils"
 FILES_${PN} =+ "${datadir}/xml/*"
-FILES_fontconfig-utils = "${bindir}/*"
+FILES_fontconfig-utils = "${bindir}/* ${libexecdir}/*"
 
 # Work around past breakage in debian.bbclass
 RPROVIDES_fontconfig-utils = "libfontconfig-utils"