allow a single APKBUILD have multiple -openrc subpackages.

awk: cmd. line:1: warning: regexp escape sequence `\#' is not a known regexp operator

Run the loop in a subshell via a pipe so we dont need a subshell for
each iteration.

Use `if ...; then` to make code slightly more readable.

Fix a whitespace before tab while at it.

Resolves alpinelinux/abuild#71

- do not overwrite variables

srcdir is very important for abuild operation

- quoted various paths
- use a sub-shell to contain directory changing

Resolves alpinelinux/abuild#58

Some projects might leave files which are not writable for the current
user. The cleanup process then fails and leaves files / directories
behind.

This can easily be fixed by making everything writable before removing
the files.

Add the option 'chmod-clean' which does just that.