Guess main packages when we don't know them
Find the main package by assuming it is a prefix of the subpkgname. We do that, because in some APKBUILDs the subpkgname="" variable gets filled with a shell loop and the APKBUILD parser in pmbootstrap can't parse this right. (Intentionally, we don't want to implement a full shell parser.)
Fixes #1667 (closed)
Edited by Administrator