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]

---
 meta/classes/fontcache.bbclass | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 2bf1e4b..dcd1f04 100644
@@ -42,4 +42,4 @@ python add_fontcache_postinsts() {
         d.setVar('pkg_postrm_%s' % pkg, postrm)
 }
 
-PACKAGEFUNCS += "add_fontcache_postinsts"
+PACKAGEFUNCS =+ "add_fontcache_postinsts"

2.3.1