fontcache.bbclass: prepend to PACKAGEFUNCS instead of appending
Appending to PACKAGEFUNCS results in the font packages missing the
postinst/postrm scripts and the fontconfig cache not being generated
in /var/cache/fontconfig when creating images or installing font
packages. This is because the package data has already been emitted
by emit_pkgdata in PACKAGEFUNCS. Prepend to PACKAGEFUNCS to ensure
add_fontcache_postinsts is executed before emit_pkgdata.
[YOCTO #7410]
Signed-off-by: Jonathan Liu <net147@gmail.com> Signed-off-by: Armin Kuster <akuster808@gmail.com>
