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/barcode/build.sh

@@ -11,4 +11,3 @@ TERMUX_PKG_BUILD_DEPENDS="gettext"
 termux_step_pre_configure() {
 	CPPFLAGS+=" -I$TERMUX_PREFIX/share/gettext"
 }
-

packages/indent/build.sh

@@ -8,4 +8,3 @@ TERMUX_PKG_SHA256=b745a5dfc68f86a483d7f96dc1cda7aafd1e78ecba3c7d8ad304709e91e1de
 TERMUX_PKG_DEPENDS="libandroid-support"
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS="ac_cv_func_setlocale=no"
 TERMUX_PKG_RM_AFTER_INSTALL="bin/texinfo2man"
-