Fix #731: Create symlinks for noarch-subpackages (#740)

* apkindex:
  * Also parse the architecture field
* symlink_noarch_package:
  * Renamed to symlink_noarch_packages
  * Always work on all packages (so we don't need to guess which
    subpackages have been generated after a certain build)
  * Get invoked when running 'pmbootstrap index'
  * Use 'apk index' to generate one index, where the architecture
    does not get rewritten (abuild does that by default, due to
    Alpine's repos not having a 'noarch' folder and diverging from
    that doesn't make things easier for us). That goes super fast,
    and then we know which packages are noarch packages and can
    create the symlinks.
* Made output less verbose:
  * Use -q for 'apk index' when calling it directly (when it gets
    called by abuild we can't control that)
  * Output that the APKINDEXes get reindexed only to the 'pmbootstrap
    log'.

main/postmarketos-base/APKBUILD

@@ -1,6 +1,6 @@
 pkgname=postmarketos-base
 pkgver=3
-pkgrel=7
+pkgrel=8
 pkgdesc="Meta package for minimal postmarketOS base"
 url="https://github.com/postmarketOS"
 arch="noarch"