user/arcticfox: Provide firefox-esr with low ver

This allows us to put 'firefox-esr' back in the Standard case of Horizon,
because on PPC where firefox-esr isn't available APK will fall back to
Arctic Fox.  But on platforms where the real Firefox is available, it will
install that.

user/arcticfox/APKBUILD

@@ -25,6 +25,7 @@ source="arcticfox-$pkgver.tar.gz::https://github.com/rmottola/Arctic-Fox/archive
 	stackwalk-x86-ppc.patch
 	"
 builddir="$srcdir/Arctic-Fox-$pkgver"
+provides="firefox-esr=$pkgver-r$pkgrel"
 _mozappdir="/usr/lib/$pkgname-$pkgver"
 # Vendors its own NSS for now until upstream is compatible with latest versions
 somask="libfreeblpriv3.so liblgpllibs.so libmozgtk.so libmozsqlite3.so