openembedded-core, meta/recipes-support/icu, has icu version 58.2.
however, firefox and seamonkey linked against this are unstable.

for my layer, using icu 56.1, same as used in both firefox 45.9 and
seamonkey 2.48b1.

the icu recipe is taken from openembedded-core krogoth release, which
is 56.1.

the patches are those from krogoth, as well as from seamonkey.
