cross/*-armhf: rebuild packages because of new hostspec

Commit 915c7d8 ("functions: adjust armhf triplet") in abuild changes the hostspec for armhf from armv6-alpine-linux-muslgnueabihf to armv6-alpine-linux-musleabihf and as our cross packages use the hostspec directly, this resulted in a discrepancy between what abuild says and what is in our package. Rebuild the armhf packages for that - and adjust some of the APKBUILDs to not use the $pkgrel variable directly.

Fixes pmbootstrap#1784 (closed)

p.s.: I hope my commit message is good enough @ollieparanoid 😉