main/gimp: security upgrade to 2.8.18 (CVE-2016-4994)

fixes #5858

main/gimp/APKBUILD

 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=gimp
-pkgver=2.8.16
+pkgver=2.8.18
 pkgrel=0
 pkgdesc="GNU Image Manipulation Program"
 url="http://www.gimp.org/"
@@ -52,6 +52,6 @@ package() {
 	ln -s gimptool-2.0 "$pkgdir/usr/bin/gimptool" || return 1
 }
 
-md5sums="30e0a1b7c18b0e3415f4ac54567252ac  gimp-2.8.16.tar.bz2"
-sha256sums="95e3857bd0b5162cf8d1eda8c78b741eef968c3e3ac6c1195aaac2a4e2574fb7  gimp-2.8.16.tar.bz2"
-sha512sums="480b49a7fc7775aa924bf2e7a5a5165b94df1318fc8439faf2e4263dd26efbca9d1d8ccc5b9b52114c33d2363e087d5a364fab86077c27bc19e58383880b13fd  gimp-2.8.16.tar.bz2"
+md5sums="5adaa11a68bc8a42bb2c778fee4d389c  gimp-2.8.18.tar.bz2"
+sha256sums="39dd2247c678deaf5cc664397d3c6bd4fb910d3472290fd54b52b441b5815441  gimp-2.8.18.tar.bz2"
+sha512sums="64b259aa5aa9d5afbf1da148ec7f162841f62db2f903c480710273362df62f00344e276b705a13619855e54948aabcd1d9a3788993360f2a52a58189b62fec2f  gimp-2.8.18.tar.bz2"