explicitly set maintainer for each package

In issue https://github.com/termux/termux-packages/issues/6160 I have found
that community repo "its-pointless.github.io" specifies us as maintainer
for its packages. This is NOT TRUE and potentially misleads people using
these packages.

Now TERMUX_PKG_MAINTAINER will contain a default value which is neutral
and not specify maintainer. So all packages now have to override it to
the correct value.

[skip ci]
%ci:no-build

packages/polipo/build.sh

@@ -23,4 +23,3 @@ termux_step_post_make_install() {
 termux_step_post_massage() {
 	mkdir -p "$TERMUX_PKG_MASSAGEDIR/$TERMUX_PREFIX"/var/cache/polipo
 }
-