The apkbuild parser could not handle cases where a line ends in a
comment but the value is not quoted.
E.g. this:
pkgver=1.0 # I'm a comment, look at me
was being parsed to a value like this:
1.0 # I'm a comment, look at me
... which is obviously wrong. This strips off any trailing comment on
the line, so it's parsed to the correct value.
fixes#2087